Vehcile air conditioning apparatus

ABSTRACT

A vehicle air conditioning apparatus is provided that can extend the mileage of a vehicle by reducing the power consumed by the operation of a compressor and a heater. When a required quantity of heating Q_req is acquired, the minimum power sharing ratio between quantity of heat release Q_hpof a water-refrigerant heat exchanger  22  and quantity of heat release Q_htrof a water heater  32  is calculated, which allows the power consumption W_total to be minimized, and a compressor  21  and the water heater  32  is operated based on the result of the calculation.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/981,061 filed Jul. 22, 2013 which is a U.S. national stage ofapplication No. PCT/JP2012/050377 filed Jan. 11, 2012 which claimspriority of Japanese Application No.: 2011-010674 filed on Jan. 21,2011, Japanese Application No.: 2011-040131 filed on Feb. 25, 2011, andJapanese Application No.: 2011-040133 filed on Feb. 25, 2011 thedisclosure contents of all of which are hereby incorporated byreference.

TECHNICAL FIELD

The present invention relates to a vehicle air conditioning apparatusapplicable to, for example, electric cars.

BACKGROUND ART

Conventionally, this sort of vehicle air conditioning apparatusincludes: a compressor driven by an engine as a power source of avehicle; a radiator provided outside the vehicle interior; and a heatexchanger provided inside the vehicle interior. With this vehicle airconditioning apparatus, a cooling operation is performed by: releasingthe heat from the refrigerant discharged from the compressor in theradiator; absorbing the heat into the refrigerant in the heat exchanger;and supplying the air subjected to a heat exchange with the refrigerantin the heat exchanger to the vehicle interior. In addition, such aconventional vehicle air conditioning apparatus includes a heater coreand perform a heating operation by: releasing the exhaust heat from thecooling water used to cool the engine in the heater core; and blowingthe air subjected to a heat exchange with the cooling water in theheater core to the vehicle interior. Moreover, such a conventionalvehicle air conditioning apparatus performs a heating and dehumidifyingoperation by: cooling the air to be supplied to the vehicle interior toa required absolute temperature in the heat exchanger fordehumidification; heating the cooled and dehumidified air in the heatexchanger to a desired temperature in the heater core; and blowing theheated air to the vehicle interior.

The above-mentioned vehicle air conditioning apparatus uses the exhaustheat from the engine as a heat source to heat the air for a heatingoperation, or a heating and dehumidifying operation. Generally, anelectric car uses an electric motor as a power source, and it isdifficult to acquire the exhaust heat that can heat the air to besupplied to the vehicle interior by using the electric motor without anengine. Therefore, the above-mentioned vehicle air conditioningapparatus is not applicable to electric cars.

To address this issue, a vehicle air conditioning apparatus has beenknown in the art, as applicable to electric cars. The vehicle airconditioning apparatus includes a refrigerant circuit having an electriccompressor, an indoor heat exchanger and an outdoor heat exchanger; andan electric heater, and perform a heating operation to heat the vehicleinterior by using either or both the heat radiated from the indoor heatexchanger by driving the compressor and the heat radiated from theheater (see, for example, Patent Literature 1).

Also, another vehicle air conditioning apparatus has been known in theart, as applicable to electric cars. The vehicle air conditioningapparatus includes: an electric compressor; a heat medium heatingradiator that releases the heat from refrigerant to heat the heatmedium; an air cooling heat exchanger that absorbs the heat into therefrigerant to cool the air blowing to the vehicle interior side; anoutdoor heat exchanger that is provided outside the vehicle interior andthat performs a heat exchange between the outdoor air and therefrigerant to release the heat from the refrigerant or absorb the heatinto the refrigerant; a heat medium circuit that allows the heat mediumheated in the heat medium heating radiator to flow through; an airheating radiator that releases the heat from the heat medium flowingthrough the heat medium circuit to heat the air blowing to the vehicleinterior; and a heat medium heater that heats the heat medium flowingthrough the heat medium circuit by electric power (see, for example,Patent Literature 2). This vehicle air conditioning apparatus performs aheating operation by: releasing the heat from the refrigerant dischargedfrom the compressor in the heat medium heating radiator; and absorbingthe heat into the refrigerant after the heat release in the outdoor heatexchanger. Moreover, this vehicle air conditioning apparatus performs aheating and dehumidifying operation by: releasing the heat from therefrigerant discharged from the compressor in the heat medium heatingradiator; and absorbing the heat into the refrigerant after the heatrelease in the air cooling heat exchanger and the outdoor heatexchanger. With this vehicle air conditioning apparatus, the heat mediumheater can heat the heat medium circulating in the heat medium circuit.

With the vehicle air conditioning apparatus, if the heating operation isperformed while the outdoor air temperature is low, the evaporatingtemperature of the refrigerant drops in the outdoor heat exchanger, sothat a frost is likely to be formed on the outdoor heat exchanger. If afrost is formed on the outdoor heat exchanger, the outdoor heatexchanger cannot acquire required quantity of heat. This causes adecrease in the performance of the heating operation.

To address this issue, a vehicle air conditioning apparatus has beenknown in the art, which performs a defrost operation to remove a frostformed on the outdoor heat exchanger (see, for example, PatentLiterature 1).

CITATION LIST Patent Literature

-   PTL1: Japanese Patent Application Laid-Open No. HEI7-52636-   PTL2: Japanese Patent Application Laid-Open No. HEI8-197937

SUMMARY OF INVENTION Technical Problem

With such a vehicle air conditioning apparatus applicable to electriccars, the electric power for driving the vehicle is used to operate thecompressor and the heater. Therefore, if the air-conditioning load islarge, most of the electric power for driving the vehicle is consumed tooperate the compressor, and therefore the mileage of the vehicle islikely to drop.

It is therefore an object of the present invention to provide a vehicleair conditioning apparatus that can extend the mileage of a vehicle byreducing the power consumption to operate the compressor and the heater.

In a case in which the outdoor air temperature is low, the vehicle airconditioning apparatus applicable to electric cars uses the heat mediumheater to secure the required quantity of heat, because the outdoor heatexchanger cannot acquire the sufficient quantity of heat. However, theheat medium heater consumes a large amount of electric power, andtherefore, if the heat medium heater is operated for heating for a longtime, most of the electric power for driving the vehicle is consumed bythe heat medium heater. As a result, the mileage of the vehicle islikely to drop.

It is therefore an object of the present invention to provide a vehicleair conditioning apparatus that can prevent the mileage of the vehiclefrom dropping by reducing the use of the heat medium heater as far aspossible.

When the vehicle air conditioning apparatus is applied to an electriccar, the power consumption by performing a defrost operation is higherthan a normal heating operation. Therefore, if a defrost operation isperformed while the vehicle is running, the electric power for drivingthe vehicle is used by the defrost operation, and therefore the mileageof the vehicle drops. Then, if the defrost operation is performed whilethe battery power for driving the vehicle and for a heating operation isinsufficient, the vehicle might become impossible to run before arrivingat the destination because the battery power is consumed for the defrostoperation.

It is therefore an object of the present invention to provide a vehicleair conditioning apparatus that can extend the mileage of the vehicle byreducing the power consumption to perform the defrost operation when thebattery power becomes insufficient while the vehicle is running.

Solution to Problem

In order to achieve the above described objects, the vehicle airconditioning apparatus according to the present invention includes: arefrigerant circuit including an electric compressor, an indoor heatexchanger and an outdoor heat exchanger, the indoor heat exchanger beingconfigured to release heat by operating the compressor; and an electricheater configured to release heat, wherein a vehicle interior can beheated by at least one of the heat released from the indoor heatexchanger and the heat released from the heater, the vehicle airconditioning apparatus further including: a minimum power sharing ratiocalculation part configured to calculate a sharing ratio of operationbetween the compressor and the heater, the sharing ratio allowing powerconsumption to be minimized when required quantity of heating for aheating operation is acquired; and a first control part configured tocontrol the compressor and the heater based on a result of a calculationby the minimum power sharing calculation part.

Therefore, it is possible to control to operate the compressor and theheater at the sharing ratio that allows the power consumption to beminimized, and consequently to acquire the required quantity of heatingwith the minimum power consumption.

In addition, in order to achieve the above described objects, thevehicle air conditioning apparatus according to the present inventionincludes: a compressor configured to compress and discharge refrigerant;a heat medium heating radiator configured to release heat from therefrigerant and heat the heat medium; an air cooling heat exchangerconfigured to absorb the heat into the refrigerant and to cool airblowing to a vehicle interior; an outdoor heat exchanger providedoutside the vehicle interior and configured to release the heat from orabsorb the heat into the refrigerant by performing a heat exchangebetween the refrigerant and outdoor air; a heat medium circuitconfigured to allow the heat medium heated by the heat medium heatingradiator to flow through; an air heating radiator configured to releaseheat from the heat medium flowing through the heat medium circuit and toheat the air blowing to the vehicle interior; and a heat medium heaterconfigured to be able to heat the heat medium flowing through the heatmedium circuit by electric power, wherein: a heating operation isperformed by releasing the heat from the refrigerant discharged from thecompressor in the heat medium heating radiator and absorbing the heatinto the refrigerant after the heat release in the outdoor heatexchanger; a heating and dehumidifying operation is performed byreleasing the heat from the refrigerant discharged from the compressorin the heat medium heating radiator and absorbing the heat into therefrigerant after the heat release in the air cooling heat exchanger andthe outdoor heat exchanger; and the heat medium heater can heat the heatmedium flowing through the heat medium circuit, the vehicle airconditioning apparatus further including: a heat medium temperatureestimating part configured to estimate a temperature of the heat mediumthat is heated by the heat medium heating radiator and flows through theheat medium circuit; an insufficient-quantity-of-heat calculation partconfigured to calculate an insufficient quantity of heat during one ofthe heating operation and the heating and dehumidifying operation, basedon a result of an estimation by the heat medium temperature estimatingpart; and a heat medium heater control part configured to control theheat medium heater, based on the insufficient quantity of heatcalculated by the insufficient-quantity-of-heat calculation part.

Therefore, it is possible to operate the heat medium heater according tothe insufficient quantity of heat calculated by theinsufficient-quantity-of-heat calculation part, and consequently tocompensate for only the insufficient heat release in the heat mediumheating radiator by operating the heat medium heater.

In addition, in order to achieve the above described objects, thevehicle air conditioning apparatus according to the present inventionincludes: a compressor configured to compress and discharge refrigerant;an indoor heat exchanger provided in a vehicle interior; and an outdoorheat exchanger provided outside the vehicle interior, wherein thevehicle interior is heated by releasing heat from the refrigerantdischarged from the compressor in the indoor heat exchanger, andabsorbing the heat into the refrigerant in the outdoor heat exchanger,the vehicle air conditioning apparatus further including: a frostformation determination part configured to determine whether or not afrost is formed on the outdoor heat exchanger; a defrost part configuredto perform a defrost operation to remove the frost formed on the outdoorheat exchanger when the frost formation determination part determinesthat the frost is formed on the outdoor heat exchanger; a battery powerdetection part configured to detect a power of a battery that suppliespower for driving a vehicle and for performing a heating operation; adefrost restriction part configured to restrict the defrost part fromperforming the defrost operation when the power of the battery detectedby the battery power detection part is a predetermined level or lower; acharge determination part configured to determine whether or not thebattery is being charged; and a cancellation part configured to cancelthe restriction on the performing of the defrost operation by thedefrost restriction part when the charge determination part determinesthat the battery is being charged.

Therefore, the defrost operation is not performed when the power of thebattery is a predetermined level or lower but is performed when thebattery is being charged. As a result, when becoming insufficient whilethe vehicle is running, the power of the battery is used for running thevehicle.

Advantageous Effect of the Invention

According to the present invention, the quantity of heat required for aheating operation can be obtained with the minimum power consumption,and therefore it is possible to reduce the electric power consumed bythe heating operation or heating and dehumidifying operation. As aresult, it is possible to extend the mileage of the vehicle.

In addition, according to the present invention, only an insufficientquantity of heat release in the heat medium heating radiator iscompensated by operating the heat medium heater. By this means, it ispossible to minimally operate the heat medium heater to reduce the powerconsumption for driving the vehicle. As a result, it is possible toprevent the mileage of the vehicle from dropping.

Moreover, according to the present invention, when the battery powerbecomes insufficient while the vehicle is running, it is possible toeffectively use the battery power in order to drive the vehicle.Therefore, it is possible to extend the mileage of the vehicle.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing a vehicle air conditioning apparatusaccording to Embodiment 1 of the present invention;

FIG. 2 is a block diagram showing a control system;

FIG. 3 is a schematic view showing the vehicle air conditioningapparatus performing a cooling operation and a cooling and dehumidifyingoperation;

FIG. 4 is a schematic view showing the vehicle air conditioningapparatus performing a heating operation;

FIG. 5 is a schematic view showing the vehicle air conditioningapparatus performing a first heating and dehumidifying operation;

FIG. 6 is a schematic view showing the vehicle air conditioningapparatus performing a second heating and dehumidifying operation;

FIG. 7 is a schematic view showing the vehicle air conditioningapparatus performing a defrost operation;

FIG. 8 is a flowchart showing a process to control quantity of heating;

FIG. 9 is a flowchart showing a process to control power-limitedoperation according to Embodiment 2 of the present invention;

FIG. 10 is a schematic view showing the vehicle air conditioningapparatus according to Embodiment 3 of the present invention;

FIG. 11 is a block diagram showing a control system;

FIG. 12 is a schematic view showing the vehicle air conditioningapparatus performing the cooling operation and the cooling anddehumidifying operation;

FIG. 13 is a schematic view showing the vehicle air conditioningapparatus performing the heating operation;

FIG. 14 is a schematic view showing the vehicle air conditioningapparatus performing the first heating and dehumidifying operation;

FIG. 15 is a schematic view showing the vehicle air conditioningapparatus performing the second heating and dehumidifying operation;

FIG. 16 is a schematic view showing the vehicle air conditioningapparatus performing the defrost operation;

FIG. 17 is a flowchart showing a process to control water temperature;

FIG. 18 is a flowchart showing a process to control quantity of heating;

FIG. 19 is a flowchart showing a process to control a water heater;

FIG. 20 is a flowchart showing a process to control operation switching;

FIG. 21 is a flowchart showing a process to control the defrostoperation;

FIG. 22 is a flowchart showing a process to control compensation forquantity of heating;

FIG. 23 is a flowchart showing a process to control quantity of heatingaccording to Embodiment 4 of the present invention;

FIG. 24 is a flowchart showing a process to control quantity of heatingaccording to Embodiment 5 of the present invention;

FIG. 25 is a flowchart showing a process to control quantity of heatingaccording to Embodiment 6 of the present invention;

FIG. 26 is a flowchart showing a process to control the water heateraccording to Embodiment 7 of the present invention;

FIG. 27 is a flowchart showing a process to control the water heateraccording to Embodiment 8 of the present invention;

FIG. 28 is a schematic view showing the vehicle air conditioningapparatus according to Embodiment 9 of the present invention;

FIG. 29 is a block diagram showing a control system;

FIG. 30 is a schematic view showing the vehicle air conditioningapparatus performing the cooling operation and the cooling anddehumidifying operation;

FIG. 31 is a schematic view showing the vehicle air conditioningapparatus performing the heating operation;

FIG. 32 is a schematic view showing the vehicle air conditioningapparatus performing the first heating and dehumidifying operation;

FIG. 33 is a schematic view showing the vehicle air conditioningapparatus performing the second heating and dehumidifying operation;

FIG. 34 is a schematic view showing the vehicle air conditioningapparatus performing the defrost operation;

FIG. 35 is a flowchart showing a process to control the defrostoperation;

FIG. 36 is a flowchart showing a process to control the defrostoperation according to Embodiment 10 of the present invention;

FIG. 37 is a flowchart showing a process to control the defrostoperation according to Embodiment 11 of the present invention;

FIG. 38 is a flowchart showing a process to control the defrostoperation according to Embodiment 12 of the present invention; and

FIG. 39 is a flowchart showing a process to control the defrostoperation according to Embodiment 13 of the present invention.

DESCRIPTION OF EMBODIMENTS

FIG. 1 to FIG. 8 show Embodiment 1 of the present invention.

The vehicle air conditioning apparatus according to the presentinvention is applicable to an electric car that is run by electric powerand that is driven by the electric power of a battery to be used to runthe electric car. As shown in FIG. 1, this vehicle air conditioningapparatus includes an air conditioning unit 10 provided in the vehicleinterior, and a refrigerant circuit 20 and a water circuit 30 that areformed across the vehicle interior and the outdoor.

The air conditioning unit 10 includes an air flow passage 11 that allowsthe air to be supplied to the vehicle interior to pass through. Anoutdoor air inlet 11 a and an indoor air inlet 11 b are provided in thefirst end side of the air flow passage 11. The outdoor air inlet 11 a isconfigured to allow the outdoor air to flow into the air flow passage11, and the indoor air inlet 11 b is configured to allow the indoor airto flow into the air flow passage 11. Meanwhile, a foot outlet 11 c, avent outlet 11 d and a defroster outlet 11 e are provided in the secondend side of the air flow passage 11. The foot outlet 11 c is configuredto allow the air flowing through the air flow passage 11 to blow to thefeet of the passengers in the vehicle. The vent outlet 11 d isconfigured to allow the air flowing through the air flow passage 11 toblow to the upper bodies of the passengers in the vehicle. The defrosteroutlet 11 e is configured to allow the air flowing through the air flowpassage 11 to blow to the interior surface of the front window.

An indoor fan 12 such as a sirocco fan configured to allow the air toflow through the air flow passage 11 from end to end is provided in thefirst end side of the air flow passage 11. This indoor fan 12 is drivenby the electric motor 12 a.

Also, in the first end side of the air flow passage 11, an inletswitching damper 13 configured to open one of the outdoor air inlet 11 aand the indoor air inlet 11 b and to close the other. This inletswitching damper 13 is driven by the electric motor 13 a. When the inletswitching damper 13 closes the indoor air inlet 11 b and opens theoutdoor air inlet 11 a, the mode is switched to an outdoor air supplymode in which the airflows from the outdoor air inlet 11 a into the airflow passage 11. Meanwhile, when the inlet switching damper 13 closesthe outdoor air inlet 11 a and opens the indoor air inlet 11 b, the modeis switched to an indoor air circulation mode in which the air flowsfrom the indoor air inlet 11 b into the air flow passage 11. Moreover,when the inlet switching damper 13 is placed between the outdoor airinlet 11 a and the indoor air inlet 11 b and the outdoor air inlet 11 aand the indoor air inlet 11 b open, the mode is switched to a two-waymode in which the air flows from both the outdoor air inlet 11 a and theindoor air inlet 11 b into the air flow passage 11 according to theopening ratio of the outdoor air inlet 11 a and the indoor air inlet 11b.

Outlet switching dampers 13 b, 13 c and 13 d configured to open andclose the foot outlet 11 c, the vent outlet 11 d and the defrosteroutlet 11 e are provided in the foot outlet 11 c, the vent outlet 11 dand the defroster outlet 11 e, respectively, in the second side of theair flow passage 11. These outlet switching dampers 13 b, 13 c and 13 dare configured to move together by a linkage and are opened and closedby the electric motor 13 e. Here, when the outlet switching dampers 13b, 13 c and 13 d open the foot outlet 1 c, close the bent outlet 11 dand slightly open the defroster outlet 11 e, most of the air flowingthrough the air flow passage 11 blows out of the foot outlet 11 c andthe remaining air blows out of the defroster outlet 11 e. This mode isreferred to as “foot mode.” Meanwhile, when the outlet switching dampers13 b, 13 c and 13 d close the foot outlet 11 c and the defroster outlet11 e, and open the vent outlet 11 d, all the air flowing through the airflow passage 11 blows out of the vent outlet 11 d. This mode is referredto as “vent mode.” In addition, when the outlet switching dampers 13 b,13 c and 13 d open the foot outlet 11 c and the vent outlet 11 d, andclose the defroster outlet 11 e, the air flowing through the air flowpassage 11 blows out of the foot outlet 11 c and the vent outlet 11 d.This mode is referred to as “bi-level mode.” Moreover, when the outletswitching dampers 13 b, 13 c and 13 d close the foot outlet 11 c and thevent outlet 11 d, and open the defroster outlet 11 e, the air flowingthrough the air flow passage 11 blows out of the defroster outlet 11 e.This mode is referred to as “defroster mode.” Furthermore, when theoutlet switching dampers 13 b, 13 c and 13 d close the vent outlet 11 dand open the foot outlet 11 c and the defroster outlet 11 e, the airflowing through the air flow passage 11 blows out of the foot outlet 11c and the defroster outlet 11 e. This mode is referred to as“defroster-foot mode.” Here, in the bi-level mode, the air flow passage11, the foot outlet 11 c, the vent outlet 11 d, and a heat exchanger anda radiator which will be described later, are arranged and configuredsuch that the temperature of the air blowing out of the foot outlet 11 cis higher than the temperature of the air blowing out of the vent outlet11 d.

A heat exchanger 14 is provided in the air flow passage 11 in thedownstream of the air flow from the indoor fan 12. The heat exchanger 14is configured to cool and dehumidify the air flowing through the airflow passage 11. In addition, a radiator 15 is provided in the air flowpassage 11 in the downstream of the air flow from the heat exchanger 14.The radiator 15 is configured to heat the air flowing through the airflow passage 11. The heat exchanger 14 is a heat exchanger that isconstituted by fins and tubes and that is configured to perform heatexchange between the refrigerant flowing through the refrigerant circuit20 and the air flowing through the air flow passage 11. Meanwhile, theradiator 15 is a heat exchanger that is constituted by fins and tubesand that is configured to perform heat exchange between the waterflowing through the water circuit 30 and the air flowing through the airflow circuit 11.

An air mix damper 16 is provided between the heat exchanger 14 and theradiator 15 in the air flow passage 11 and is configured to control thepercentage of the air to be heated, which is flowing through the airflow passage 11. The air mix damper 16 is driven by the electric motor16 a. When the air mix damper 16 is disposed in the air flow passage 11in the upstream of the radiator 15, the percentage of the air subjectedto a heat exchange in the radiator 15 is reduced. Meanwhile, when theair mix damper 16 is moved to a position other than the radiator 15 inthe air flow passage 11, the percentage of the air subjected to a heatexchange is increased. In the air flow passage 11, when the air mixdamper 16 closes the upstream side of the radiator 15 and opens theportion other than the radiator 15, the opening degree is 0%, and, onthe other hand, when the air mix damper 16 opens the upstream side ofthe radiator 15 and closes the portion other than the radiator 15, theopening degree is 100%.

The refrigerant circuit 20 includes: the heat exchanger 14; a compressor21 configured to compress refrigerant; a water-refrigerant heatexchanger 22 configured to perform a heat exchange between therefrigerant and the water flowing through the water circuit 30; anoutdoor heat exchanger 23 configured to perform a heat exchange betweenthe refrigerant and the outdoor air; an indoor heat exchanger 24configured to perform a heat exchange between the refrigerant flowinginto the heat exchanger 14 and the refrigerant flowing out of the heatexchanger 14; a three-way valve 25 configured to switch the passage ofthe refrigerant; first to fourth solenoid valves 26 a to 26 d; first andsecond check valves 27 a and 27 b; and first and second expansion valves28 a and 28 b configured to decompress the refrigerant. These componentsare connected to each other by a copper pipe or an aluminum pipe. Thecompressor 21 and the outdoor heat exchanger 23 are disposed outside thevehicle interior. The compressor 21 is driven by the electric motor 21a. The outdoor heat exchanger 23 is provided with an outdoor fan 29configured to perform heat exchange between the outdoor air and therefrigerant when the vehicle stops. The outdoor fan 29 is driven by theelectric motor 29 a.

To be more specific, one side of the water-refrigerant heat exchanger 22into which the refrigerant flows is connected to one side of thecompressor 21 from which the refrigerant is discharged to form therefrigerant flow passage 20 a. In addition, the input side of theoutdoor heat exchanger 23 into which the refrigerant flows is connectedto the output side of the water-refrigerant heat exchanger 22 from whichthe refrigerant is discharged, thereby to form the refrigerant flowpassage 20 b. The refrigerant flow passage 20 b is provided with thethree-way valve 25. The one side of the three-way valve 25 from whichthe refrigerant is discharged and another side from which therefrigerant is discharged are parallel to one another and are connectedto the input side of the outdoor heat exchanger 23 into which therefrigerant flows and thereby to form the refrigerant flow passages 20 cand 20 d. The refrigerant flow passage 20 d is provided with the firstexpansion valve 28 a and the first check valve 27 a in the order fromthe upstream of the flow of the refrigerant. The input side of thecompressor 21 into which the refrigerant is sucked and the part of therefrigerant flow passage 20 d between the three-way valve 25 and thefirst expansion valve 28 a are connected in parallel to the output sideof the outdoor heat exchanger 23 from which the refrigerant isdischarged, thereby to form the refrigerant flow passage 20 e and 20 f.The refrigerant flow passage 20 e is provided with the first solenoidvalve 26 a. The refrigerant flow passage 20 f is provided with thesecond solenoid valve 26 b and the second check valve 27 b in the orderfrom the upstream of the flow of the refrigerant. The input side of theinterior heat exchanger 24 into which high-pressure refrigerant flows isconnected to the part of the refrigerant flow passage 20 d between thethree-way valve 25 and the first expansion valve 28 a, thereby to formthe refrigerant flow passage 20 g. The refrigerant passage 20 g isprovided with the third solenoid valve 26 c. The input side of the heatexchanger 14 into which the refrigerant flow is connected to the outputside of the indoor heat exchanger 24 from which the high-pressurerefrigerant is discharged, thereby to provide the refrigerant flowpassage 20 h. The refrigerant flow passage 20 h is provided with thesecond expansion valve 28 b. The input side of the indoor heat exchanger24 into which low-pressure refrigerant flows is connected to the outputside of the heat exchanger 14 from which the refrigerant is discharged,thereby to form the refrigerant flow passage 20 i. The part of therefrigerant flow passage 20 e between the first solenoid valve 26 a andthe input side of the compressor 21 into which the refrigerant is suckedis connected to the output side of the indoor heat exchanger 24 fromwhich the low-pressure refrigerant is discharged, thereby to provide therefrigerant flow passage 20 j. The input side of the outdoor heatexchanger 23 into which the refrigerant flows is connected to therefrigerant flow passage 20 a, thereby to provide the refrigerant flowpassage 20 k. The refrigerant flow passage 20 k is provided with thefourth solenoid valve 26 d.

The water circuit 30 includes the radiator 15, the water-refrigerantheat exchanger 22, a pump 31 configured to pump the water as heat mediumand a water heater 32 such as an electric heater configured to heatwater by electric power. These components are connected by a copper pipeor an aluminum pipe. To be more specific, the input side of thewater-refrigerant heat exchanger 22 into which water flows is connectedto output side of the pump 31 from which the water is discharged,thereby to form a water flow passage 30 a. The input side of the waterheater 32 into which the water flows is connected to the output side ofthe water-refrigerant heat exchanger 22 from which the water isdischarged, thereby to from a water flow passage 30 b. The input side ofthe radiator 15 into which the water flows is connected to the outputside of the water heater 32 from which the water is discharged, therebyto form a water flow passage 30 c. The input side of the pump 31 intowhich the water is sucked is connected to the output side of theradiator 15 from which the water flows, thereby to from a water flowpassage 30 d. The pump 31 is driven by the electric motor 31 a.

The vehicle air conditioning apparatus also includes a controller 40that controls the temperature and the humidity of the vehicle interiorto be the preset temperature and humidity.

The controller 40 includes a CPU, a ROM and a RAM. In the controller,upon receiving an input signal from a device connected to the inputside, the CPU reads the program stored in the ROM according to the inputsignal, stores the state detected by the input signal on the RAM andtransmits an output signal to a device connected to the output side.

As shown in FIG. 2, an outdoor air temperature sensor 41 configured todetect temperature Tam outside the vehicle interior; an indoor airtemperature sensor 42 configured to detect temperature Tr in the vehicleinterior; an intake temperature sensor 43 configured to detecttemperature Ti of the air flowing into the air flow passage 11; a cooledair temperature sensor 44 configured to detect temperature Te of the airhaving been cooled in the heat exchanger 14; a heated air temperaturesensor 45 configured to detect temperature Tc of the air having beenheated in the radiator 15; an indoor air humidity sensor 46 configuredto detect humidity Th in the vehicle interior; a refrigerant temperaturesensor 47 configured to detect temperature Thex of the refrigerant afterthe heat exchange in the outdoor heat exchanger 23; an insolation sensor48 such as a photo sensor configured to detect amount of insolation Ts;a velocity sensor 49 configured to detect velocity V of the vehicle; anoperation part 50 configured to set modes regarding to target settingtemperature Tset and the switching of the operation; and a pressuresensor 51 configured to detect pressure Pd in the high-pressure side ofthe refrigerant circuit 20 are connected to the input side of thecontroller 40.

As shown in FIG. 2, an electric motor 12 a for driving the indoor fan12; an electric motor 13 a for driving the inlet switching damper 13; anelectric motor 13 e for driving the outlet switching dampers 13 b, 13 cand 13 d; an electric motor 16 a for driving the air mix damper 16; anelectric motor 21 a for driving the compressor 21; the three-way valve25; the first to fourth solenoid valves 26 a, 26 b, 26 c and 26 d; anelectric motor 29 a for driving the outdoor fan 29; an electric motor 31a for driving the pump 31; the water heater 32; and a display part 52such as a liquid crystal display configured to display the indoor airtemperature Tr or information on such as an operation state areconnected to the output side of the controller 40.

The vehicle air conditioning apparatus having the above-describedconfiguration performs cooling operation, cooling and dehumidifyingoperation, heating operation, first heating and dehumidifying operation,second heating and dehumidifying operation and defrost operation. Now,each operation will be explained.

First, the cooling operation will be explained. In the refrigerantcircuit 20, the flow passage of three-way valve is set to therefrigerant flow passage 20 c side; the second and third solenoid valves26 b and 26 c open and the first and fourth solenoid valves 26 a and 26d are closed; and the compressor 21 is operated. Meanwhile, theoperation of the pump 31 is stopped in the water circuit 30.

By this means, as shown in FIG. 3, the refrigerant discharged from thecompressor 21 flows through in this order: the refrigerant flow passage20 a; the water-refrigerant heat exchanger 22; water-refrigerant flowpassages 20 b and 20 c; the outdoor heat exchanger 23, the refrigerantflow passages 20 f, 20 d and 20 g, the high-pressure side of theinternal heat exchanger 24; the refrigerant flow passage 20 h; the heatexchanger 14; the refrigerant flow passage 20 i; the low-pressure sideof the internal heat exchanger 24; and the refrigerant flow passages 20j and 20 e, and is sucked into the compressor 21. The refrigerantflowing through the refrigerant circuit 20 releases the heat in theoutdoor heat exchanger 23 and absorbs the heat in the heat exchanger 14.Since the pump 31 is stopped in the cooling operation, heat is notreleased from refrigerant in the water-refrigerant heat exchanger 22.

In this case, in the air conditioning unit 10 during the coolingoperation, the indoor fan 12 is operated to flow the air through the airflow passage 11, and the air is subjected to a heat exchange with therefrigerant in the heat exchanger 14 and cooled. The temperature of thecooled air is the target air-blowing temperature TAO of the air to blowout of the outlets 11 c, 11 d and 11 e in order to set the temperatureof the vehicle interior to target setting temperature Tset. Then, theair at temperature Tset blows to the vehicle interior.

Next, the cooling and dehumidifying operation will be explained. In therefrigerant circuit 20, like the cooling operation, the flow passage ofthe three-way valve 25 is set to the refrigerant flow passage 20 c side;the second and third solenoid valves 26 b and 26 c open and the firstand fourth solenoid valves 26 a and 26 d are closed; and the compressor21 is operated. In the water circuit 30, the pump 31 is operated.

By this means, as shown in FIG. 3, the refrigerant discharged from thecompressor 21 flows through in the same way as in the cooling operation.The refrigerant flowing through the refrigerant circuit 20 releases theheat in the water-refrigerant heat exchanger 22 and the outdoor heatexchanger 23, and absorbs the heat in the heat exchanger 14.

In addition, the water discharged from the pump 31 flows through in thisorder: the water-refrigerant heat exchanger 22, the water heater 32; andthe radiator 15 as indicated by the chain line of FIG. 3, and is suckedinto the pump 31. The water flowing through the water circuit 30 absorbsthe heat in the water-refrigerant heat exchanger 22 and releases theheat in the radiator 15.

In this case, in the air conditioning unit 10 during the cooling anddehumidifying operation, the indoor fan 12 is operated to flow the airthrough the air flow passage 11, and the air is subjected to a heatexchange with the refrigerant which absorbs the heat in the heatexchanger 14, and therefore is cooled and dehumidified. The air havingbeen dehumidified in the heat exchanger 14 is subject to heat exchangewith the water which releases the heat in the radiator 15, and thereforeheated. As a result, the air at the target air-blowing temperature TAOblows to the vehicle interior.

Next, the heating operation will be explained. In the refrigerantcircuit 20, the flow passage of the three-way valve 25 is set to therefrigerant flow passage 20 d side; the first solenoid valve 26 a opensand the second to fourth solenoid valves 26 b to 26 d are closed: andthe compressor 21 is operated. In the water circuit 30, the pump 31 isoperated.

By this means, as shown in FIG. 4, the refrigerant discharged from thecompressor 21 flows through this order: the refrigerant flow passage 20a; the water-refrigerant heat exchanger 22; the refrigerant flowpassages 20 b and 20 d; the outdoor heat exchanger 23; and therefrigerant flow passage 22 e, and is sucked into the compressor 21. Therefrigerant flowing through the refrigerant circuit 20 releases the heatin the water-refrigerant heat exchanger 22 and absorbs the heat in theoutdoor heat exchanger 23.

Meanwhile, as shown in FIG. 4, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22;the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22 and releases the heat in theradiator 15.

In this case, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11, and theflowing air is not subject to a heat exchange with the refrigerant inthe heat exchanger 14, but is subjected to a heat exchange with thewater in the radiator 15 and therefore is heated. As a result, the airat the target air-blowing temperature TAO blows to the vehicle interior.

Next, the first heating and dehumidifying operation will be explained.In the refrigerant circuit 20, the flow passage of the three-way valve25 is set to the refrigerant flow passage 20 d side; the first and thirdsolenoid valves 26 a and 26 c open and the second and fourth solenoidvalves 26 b and 26 d are closed; and the compressor 21 is operated.Meanwhile, the pump 31 is operated in the water circuit 30.

By this means, as shown in FIG. 5, the refrigerant discharged from thecompressor 21 flows through in this order: the refrigerant flow passage20 a; the water-refrigerant heat exchanger 22; and the refrigerant flowpassages 20 b and 20 d. Part of the refrigerant flowing through therefrigerant flow passage 20 d flows through in this order: the outdoorheat exchanger 23; and the refrigerant flow passage 20 e, and is suckedinto the compressor 21. In addition, remaining refrigerant flowingthrough the refrigerant flow passage 20 d flows through in this order:the refrigerant flow passage 20 g; the high-pressure side of theinterior heat exchanger 24; the refrigerant flow passage 20 h; the heatexchanger 14; the refrigerant flow passage 20 i; the low-pressure sideof the interior heat exchanger 24; and the refrigerant flow passages 20j and 20 e, and is sucked into the compressor 21. The refrigerantflowing through the refrigerant circuit 20 releases the heat in thewater-refrigerant heat exchanger 22 and absorbs the heat in the heatexchanger 14 and the outdoor heat exchanger 23.

Meanwhile, as shown in FIG. 5, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22;the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22 and releases the heat from theradiator 15.

In this case, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11, and theflowing air is subjected to a heat exchange with the refrigerant in theheat exchanger 14, and therefore is cooled and dehumidified. Part of theair having been dehumidified in the heat exchanger 14 is subjected to aheat exchange with the water in the radiator 15 and heated. As a result,the air at the target air-blowing temperature TAO blows into the vehicleinterior.

Next, the second heating and dehumidifying operation will be explained.In the refrigerant circuit 20, the flow passage of the three-way valve25 is set to the refrigerant flow passage side 20 d; the third solenoidvalve 26 c opens and the first, second and fourth solenoid valves 26 a,26 b and 26 d are closed; and the compressor 21 is operated. Meanwhile,the pump 31 is operated in the water circuit 30.

By this means, as shown in FIG. 6, the refrigerant discharged from thecompressor 21 flows through in this order: the refrigerant flow passage20 a; the water-refrigerant heat exchanger 22; the refrigerant flowpassages 20 b, 20 d and 20 g; the high-pressure side of the interiorheat exchanger 24; the refrigerant flow passage 20 h; the heat exchanger14; the refrigerant flow passage 20 i; the low-pressure side of theinterior heat exchanger 24; and the refrigerant flow passages 20 j and20 e, and is sucked into the compressor 21. The refrigerant flowingthrough the refrigerant circuit 20 releases the heat in thewater-refrigerant heat exchanger 22 and absorbs the heat in the heatexchanger 14.

Meanwhile, as shown in FIG. 6, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22;the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22 and releases the heat in theradiator 15.

In this case, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11, and theflowing air is subjected to a heat exchange with the refrigerant in theheat exchanger 14, and therefore is cooled and dehumidified in the sameway as in the first heating and dehumidifying operation. Part of the airdehumidified in the heat exchanger 14 is subjected to a heat exchangewith the water in the radiator 15, and therefore heated. As a result,the air at the target air-blowing temperature TAO blows to the vehicleinterior.

Next, the defrost operation will be explained. In the refrigerantcircuit 20, the flow passage of the three-way valve 25 is set to therefrigerant flow passage 20 d side; the first and fourth solenoid valves26 a and 26 d open and the second and third solenoid valves 26 d and 26c are closed; and the compressor 21 is operated. Meanwhile, the pump 31is operated in the water circuit 30.

By this means, as shown in FIG. 7, part of the refrigerant dischargedfrom the compressor 21 flows through in this order: the refrigerant flowpassage 20 a; the water-refrigerant heat exchanger 22; the refrigerantflow passages 20 b and 20 d, and flows into the outdoor heat exchanger23. In addition, the remaining refrigerant discharged from thecompressor 21 flows through the refrigerant flow passages 20 a and 20 kand flows into the outdoor heat exchanger 23. The refrigerant flowingout of the outdoor heat exchanger 23 flows through the refrigerant flowpassage 20 e, and is sucked into the compressor 21. The refrigerantflowing through the refrigerant circuit 20 releases the heat in theradiator 15, and at this time, absorbs the heat in the outdoor heatexchanger 23.

Meanwhile, as shown in FIG. 7, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22,the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22, and releases the heat in theradiator 15.

In this case, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11. The flowingair is not subjected to a heat exchange with the refrigerant in the heatexchanger 14, but is subjected to a heat exchange with the water whichreleases the heat in the radiator 15, and therefore is heated and thenblows to the vehicle interior.

While the automatic switch of the operation part 50 is turned on, thecontroller 40 performs an operation switching control process to switchamong the cooling operation, the cooling and dehumidifying operation,the heating operation, the first heating and dehumidifying operation,the second heating and dehumidifying operation, and the defrostoperation, based on indoor and outdoor environmental conditions, such astemperature.

In each operation switched by the operation switching control process,the controller 40 switches among the foot mode, the vent mode and thebi-level mode according to the target air-blowing temperature TAO. To bemore specific, when the target air-blowing temperature TAO is high, forexample, 40 degrees centigrade, the controller 40 sets the foot mode.Meanwhile, when the target air-blowing temperature TAO is low, forexample, lower than 25 degrees centigrade, the controller sets the ventmode. Moreover, when the target air-blowing temperature TAO is thetemperature between the temperature for the foot mode and thetemperature for the vent mode, the controller 40 sets the bi-level mode.

The controller 40 switches the mode of the outlets 11 c, 11 d and 11 eby using the outlet switching dampers 13 b, 13 c and 13 d, and controlsthe opening degree of the air mix damper 16 in order to set thetemperature of the air blowing out of the outlets 11 c, 11 d, and 11 eto the target air-blowing temperature TAO.

Moreover, in the heating operation or the heating and dehumidifyingoperation, the controller 40 performs a quantity-of-heating controlprocess to control quantity of heat release Q_hp of the refrigerant andquantity of heat release Q_htr of the water heater 32 in thewater-refrigerant heat exchanger 22, in order to set the temperature ofthe air blowing to the vehicle interior. Now, the operation of thecontroller 40 in this process will be explained with reference to theflowchart shown in FIG. 8.

(Step S1)

In step S1, the CPU determines whether the operation is the heatingoperation or the heating and dehumidifying operation. When determiningthat the operation is one of the heating operation and the heating anddehumidifying operation, the CPU moves the step to step S2. Meanwhile,determining that the operation is neither the heating operation nor theheating and dehumidifying operation, the CPU ends thequantity-of-heating control process.

(Step S2)

When determining that that the operation is one of the heating operationand the heating and dehumidifying operation in the step S1, the CPUcalculates required quantity of heating Qreq based on outdoor airtemperature Tam, temperature Te of the air having been cooled in theheat exchanger 14 (in case of the heating operation, temperature Ti ofthe air flowing into the air flow passage 11) and the target air-blowingtemperature TAO.

(Step S3)

In step S3, the CPU calculates a minimum power sharing ratio, which isthe sharing ratio between the quantity of heat release Q_hp of thewater-refrigerant heat exchanger 22 and the quantity of heat releaseQ_htr of the water heater 32 that allows the power consumption to beminimized when the required quantity of heating Q_req calculated in thestep 2 is outputted. A method of calculating this minimum power sharingratio will be described later.

(Step S4)

In step S4, the CPU operates the compressor 21 and the water heater 32according to the minimum power sharing ratio k calculated in the stepS3, and ends the quantity-of-heating control process. In this case, thequantity of heat release Q_hp of the refrigerant in thewater-refrigerant heat exchanger 22 and the quantity of heat releaseQ_htr of the water heater 32 are calculated based on the requiredquantity of heating Q_req and the minimum power sharing ratio k (0≦k≦1),(Q_hp=k×Qreq, Q_htr=(1−k)×Qreq).

Now, the method of calculating the minimum power sharing ratio k in thestep S3 will be explained.

A coefficient of performance (hereinafter referred to as COP) related tothe heating capability of the water-refrigerant heat exchanger 22 variesaccording to the number of rotations Nc of the compressor 21, theoutdoor air temperature Tam and the target air-blowing temperature TAO.The COP can be read from a table in which the COP is associated witheach of the number of rotations Nc of the compressor 21, the outdoor airtemperature Tam and the target air-blowing temperature Tam. The table inwhich the COP is associated with each item is obtained by, for example,experiments, simulations by a computer and so forth.

The quantity of heat release Q_hp of the water-refrigerant heatexchanger 22 constantly increases and decreases according to theincrease and decrease of the number of rotations of the compressor 21.

Moreover, power consumption W_htr of the water heater 32 constantlyincreases and decreases according to the increase and decrease of thequantity of heat release Q_htr. Meanwhile, power consumption W_hp of thewater-refrigerant heat exchanger 22 is obtained by dividing the quantityof heat release Q_hp by the COP (W_hp=Q_hp/COP).

Therefore, the minimum power sharing ratio k is the sharing ratiobetween the water-refrigerant heat exchanger 22 and the water heater 32when the total power consumption W_total of the power consumption W_hpand the power consumption W_htr is minimized on the condition that thetotal quantity of heat release Q_total of the quantity of heat releaseQ_hp and the quantity of heat release Q_htr satisfies the quantity ofheat release Q_req.

The minimum power sharing ratio k varies according to the requiredquantity of heating Q_req, the outdoor air temperature Tam and thetarget air-blowing temperature TAO. The minimum power sharing ratio k isdetermined based on a table in which the minimum power sharing ratio kis associated with each of the required quantity of hearing Q_req, theoutdoor air temperature Tam and the target air-blowing temperature TAO.The table in which the minimum power sharing ratio k is associated witheach item is obtained by, for example, experiments, simulations by acomputer and so forth.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, when the required quantity ofheating Q_req is acquired, the minimum power sharing ratio k between thequantity of heat release Q_hp of the water-refrigerant heat exchanger 22and the quantity of heat release Q_htr of the water heater 32 iscalculated, which allows the power consumption W_total to be minimized,and the compressor 21 and the water heater 32 are controlled accordingto the result of the calculation. By this means, the required output ofthe heating operation can be obtained with the minimum powerconsumption, and therefore it is possible to reduce the powerconsumption of the heating operation or the heating and dehumidifyingoperation. As a result, it is possible to extend the mileage of thevehicle.

FIG. 9 shows Embodiment 2 of the present invention. Here, the samecomponents are assigned the same reference numerals as in Embodiment 1.

This vehicle air conditioning apparatus is configured to performpower-limited operation to limit the supplied power W_total to the valueequal to or lower than predetermined limited power Wlim_AC, when thebattery power to be used to drive the vehicle is equal to or lower thana predetermined level.

During the power-limited operation, the controller 40 of this vehicleair conditioning apparatus performs a power-limited operation controlprocess that can provide the maximum quantity of heat release within therange of the limited power Wlim_AC. Now, the operation of the controller40 in this process will be explained with reference to the flowchartshown in FIG. 9.

(Step S11)

In step S11, the CPU determines whether the operation is the heatingoperation or the heating and dehumidifying operation. When determiningthat the operation is one of the heating operation and the heating anddehumidifying operation, the CPU moves the step to step S12. On theother hand, when determining that the operation is neither the heatingoperation nor the heating and dehumidifying operation, the CPU ends thispower-limited operation control process.

(Step 12)

In step the S11, when determining that the operation is one of theheating operation and the heating and dehumidifying operation, the CPUcalculates the required quantity of heating Q_req based on the outdoorair temperature Tam, the temperature Te of the air having been cooled inthe heat exchanger 14 (in case of the heating operation, the temperatureTi of the air flowing into the air flow passage 11) and the targetair-blowing temperature TAO in step S12.

(Step S13)

In step S13, the CPU calculates the minimum power sharing ratio k, whichis the sharing ratio between the quantity of heat release Q_hp of thewater-refrigerant heat exchanger 22 and the quantity of heat releaseQ_htr that allows the power consumption to be minimized when therequired quantity of heating Q_req calculated in the step 2 isoutputted. The method of calculating the minimum power sharing ratio isthe same as in the step S3 of Embodiment 1.

(Step S14)

In step S14, the CPU determines whether or not the limited-poweroperation is being performed. When determining that the limited-poweroperation is being performed, the CPU moves the step to step S15. On theother hand, when determining that the power-limited operation is notperformed, the CPU moves the step to step S24.

(Step 15)

When determining that the limited-power operation is being performed inthe step S14, the CPU, in step 15, calculates required power W_req forthe operation at the minimum power sharing ratio calculated in the stepS13.

(Step S16)

In step S16, the CPU determines whether or not the power W_reqcalculated in the step S15 is greater than the limited power Wlim_AC.When determining that the power W_req is greater than the limited powerWlim_AC, the CPU moves the step to step S17. On the other hand, whendetermining that the power W_req is equal to or smaller than the limitedpower Wlim_AC, the CPU moves the step to the step S24.

(Step S17)

When determining that the required power W_req is greater than thelimited power Wlim_AC in the step 16, the CPU calculates maximumquantity-of-heating sharing ratio k′, which is the sharing ratio betweenthe power consumption W_hp of the compressor 21 and the powerconsumption W_htr of the water heater 32 that allows the quantity ofheating to be maximized at the limited power Wlim_AC. The method ofcalculating this maximum quantity-of-heating sharing ratio k′ will bedescribed later.

(Step S18)

In step S18, the CPU operates the compressor 21 and the water heater 32according to the maximum quantity-of-heating sharing ratio k′ calculatedin the step S17. In this case, the power consumption W_hp of thecompressor 21 and the power consumption W_htr of the water heater 32 arecalculated based on the limited power Wlim_AC and the maximumquantity-of-heating sharing ratio k′ (0≦k′≦1), (W_hp=k′×Wlim_AC,W_htr=(1−k′)×Wlim_AC).

(Step S19)

In step S19, the CPU calculates the air quantity of the indoor fan 12that can maintain the target air-blowing temperature TAO at the totalquantity of heat release Q_total of the quantity of heat release Q_hpand the quantity of heat release Q_htr. To be more specific, thefollowing equation is held by: the quantity of heating Q_total;difference in temperature ΔT (degree centigrade) between temperature Tcof the air having been heated in the radiator 15 and temperature Te ofthe air before being heated in the radiator 15 (temperature Te in theheating and dehumidifying operation and temperature Ti or Te in theheating operation); specific heat of the air Cp (J/kg·K=W·sec/kg·k);density ρ (kg/m3); and flow rate G (m3/sec) of the air subjected to aheat exchange with the water in the radiator 15.

Q_total=ΔT×Cp×ρ×G

Therefore, when the quantity of heating Q_total drops during thepower-limited operation, it is possible to maintain the temperaturedifference ΔT by decreasing the flow rate G of the air. In the step S19,the air quantity of the indoor fan 12 is calculated, which can maintainthe temperature difference AT in the above-described equation.

(Step S20)

In step S20, the CPU operates the indoor fan 12 based on the airquantity calculated in the step S19. In this case, when the air quantitycalculated in the step S19 is smaller than the controllable minimum airquantity, the air quantity of the indoor fan 12 is minimized. On theother hand, when the air quantity is greater than the value not duringthe power-limited operation, the air quantity is set to a value notduring the power-limited operation.

(Step S21)

In step S21, the CPU sets the mode of the outlets to the foot mode bythe outlet switching dampers 13 b, 13 c and 13 d.

(Step S22)

In step S22, the CPU determines that the opening degree of the air mixdamper 16 is 10%.

(Step S23)

In step S23, the CPU displays that the power-limited operation is beingperformed on the display part 52.

(Step S24)

When determining that the power-limited operation is not performed inthe step 14, or when determining that the required power is lower thanthe limited power in the step S16, the CPU, in step S24, operates thecompressor 21 and the water heater 32 according to the minimum powersharing ratio k calculated in the step S3, and ends the power-limitedoperation control process. Here, the quantity of heat release Q_hp ofthe refrigerant in the water-refrigerant heat exchanger 22 and thequantity of heat release Q_htr of the water heater 32 is calculatedbased on the required quantity of heating Qreq and the minimum powersharing ratio k (0≦k≦1), (Q_hp=k×Qreq, Q_htr=(1−k)×Qreq).

Next, the method of calculating the maximum quantity-of-heating sharingratio k′ in the step S17 will be explained.

The maximum quantity-of-heating sharing ratio k′ is the sharing ratio ofthe operation between the water-refrigerant heat exchanger 22 and thewater heater 32 when the total quantity of heating Q_total of thequantity of heating Q_hp of the water-refrigerant heat exchanger 22 andthe quantity of heating Q_htr of the water heater 32 is maximized on thecondition that the total power consumption of the power consumption W_hpof the compressor 21 and the power consumption W_htr of the water heater32 is the limited power Wlim_AC.

The maximum quantity-of-heating sharing ratio k′ varies according to thelimited power Wlim_AC, the outdoor air temperature Tam, and the targetair-blowing temperature TAO. The maximum quantity-of-heating sharingratio k′ is determined based on a table in which the maximumquantity-of-heating sharing ratio k′ is associated with each of thelimited power Wlim_AC, the outdoor air temperature Tam and the targetair-blowing temperature TAO. The table in which the maximumquantity-of-heating sharing ratio k′ is associated with each item isobtained by, for example, experiments, simulations by a computer and soforth.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, it is possible to acquire therequired output of the heating operation with the minimum powerconsumption, and therefore to reduce the power consumption in theheating operation or the heating and dehumidifying operation in the sameway as in Embodiment 1. As a result, it is possible to extend themileage of the vehicle.

In addition, during the power-limited operation, the maximumquantity-of-heating sharing ratio k′ between the power consumption W_hpof the compressor 21 and the power consumption W_htr of the water heater32 is calculated, which allows the quantity of heat release Q_total tobe maximized at the limited power Wlim_AC, and the compressor 21 and thewater heater 32 are controlled based on the result of the calculation.By this means, it is possible to achieve the maximum quantity of heatrelease Q_total within the range of the limited power Wlim_AC, andtherefore to prevent the environment of the vehicle interior, such asthe temperature and the humidity from deteriorating during thepower-limited operation.

Moreover, the air quantity of the indoor fan 12 is controlled such thatthe temperature of the air blowing into the vehicle interior from theindoor fan 12 during the power-limited operation is the targetair-blowing temperature TAO of the air blowing into the vehicle interiorfrom the indoor fan 12 not during the power-limited operation. By thismeans, it is possible to prevent the air-blowing temperature fromchanging because the power-limited operation starts, and the passengersin the vehicle do not have an uncomfortable feeling because of thechange in air-blowing temperature.

In addition, when the air quantity of the indoor fan 12 calculated inthe step S19 is smaller than the controllable minimum air quantity, theair quantity of the indoor fan 12 is minimized. On the other hand, whenthe air quantity is greater than the air quantity not during thepower-limited operation, the air quantity of the indoor fan 12 is set tothe value not during the power-limited operation. By this means, it ispossible to set the air quantity of the indoor fan 12 within apredetermined range, and therefore to prevent inefficient operation anda failure of the indoor fan 12.

Moreover, the display part 52 displays that the power-limited operationis being performed on the display part 52. By this means, it is possibleto notify the passengers in vehicle that the power-limited operation isbeing performed, and therefore to prevent the passengers from making anerror of judgment that a failure has occurred.

Here, with the present embodiment, a configuration has been describedwhere the heat released from the water-refrigerant circuit 20 isabsorbed in the water flowing through the water circuit 30 via thewater-refrigerant heat exchanger 22. However, heat medium subjected to aheat exchange with refrigerant is not limited to water, but any heatmedium is applicable, which enables heat transfer, such as antifreezesolution containing ethyleneglycol and so forth.

In addition, with the present embodiment, a configuration has beendescribed where the three-way valve 25 is used to switch between therefrigerant flow passages 20 c and 20 d in the refrigerant circuit 20.It is by no means limiting. Two solenoid valves are applicable insteadof the three-way valve, and therefore it is possible to switch betweenthe refrigerant flow passages 20 c and 20 d by opening and closing thesesolenoid valves.

Moreover, with the present embodiment, a configuration has beendescribed where the display part 52 displays that the power-limitedoperation is being performed. It is by no means limiting, but anotherconfiguration is possible where the voice of a speaker is used to notifythat the power-limited operation is being performed.

Moreover, with the present embodiment, a configuration has beendescribed where the water flowing through the water circuit 30, which issubjected to the heat exchange with the refrigerant releasing the heatin the water-refrigerant heat exchanger 22 of the refrigerant circuit20, is heated by the water heater 32. It is by no means limiting. Forexample, the vehicle air conditioning apparatus may not have the watercircuit 30 but have an indoor radiator. The indoor radiator releases theheat of the refrigerant flowing through the refrigerant circuit 20directly in the air flow passage 11, and the air flowing through the airflow passage 11 may be directly heated by an electric heater. By thismeans, it is possible to produce the same effect as in the presentembodiment. Moreover, further another configuration is possible wherethe vehicle air conditioning apparatus includes an indoor radiatorconfigured to release the heat of the refrigerant flowing through therefrigerant circuit 20 directly in the air flow passage 11; a heatmedium circuit that allows the heat medium having heated by the electricheater to flow through is provided separately from the refrigerantcircuit 20; the heat of the heat medium heated by the electric heater isreleased in the air flow passage 11. By this means, it is possible toproduce the same effect as in the present embodiment.

With the present embodiment, the process including the step S3 and thestep S13 to calculate the minimum power sharing ratio k corresponds to aminimum power sharing ratio calculation part of the present invention.The minimum power sharing ratio k is the sharing ratio between thequantity of heat release Q_hp of the water-refrigerant heat exchanger 22and the quantity of heat release Q_htr of the water heater 32 thatallows the power consumption to be minimized when the required quantityof heating Q_req is outputted. In addition, with the present embodiment,the process including the step S17 to calculate the maximumquantity-of-heating sharing ratio k′ corresponds to a maximum sharingratio calculation part of the present invention. The maximumquantity-of-heating sharing ratio k′ is the sharing ratio between thepower consumption W_hp of the compressor 21 and the power consumptionW_htr of the water heater 32 that allows the quantity of heating to bemaximized at the limited power Wlim_AC. In addition, with the presentembodiment, the process including the step 19 to calculate the airquantity of the indoor fan 12, which can maintain the target air-blowingtemperature TAO at the total quantity of heat release Q_total of thequantity of heat release Q_hp and the quantity of heat release Q_htrcorresponds to an air quantity calculation part of the presentinvention. Moreover, with the present embodiment, the process includingthe step S23 to display that the power-limited operation is beingperformed on the display part 52 corresponds to an information part ofthe present invention.

FIG. 10 to FIG. 22 show Embodiment 3 of the present invention.

As shown in FIG. 10, this vehicle air conditioning apparatus includes anair conditioning unit 10 provided in the vehicle interior, and arefrigerant circuit 20 and a water circuit 30 that are formed across thevehicle interior and the outdoor.

The air conditioning unit 10 includes an air flow passage 11 that allowsthe air to be supplied to the vehicle interior to pass through. Anoutdoor air inlet 11 a and an indoor air inlet 11 b are provided in thefirst end side of the air flow passage 11. The outdoor air inlet 11 a isconfigured to allow the outdoor air to flow into the air flow passage11, and the indoor air inlet 11 b is configured to allow the indoor airto flow into the air flow passage 11. Meanwhile, a foot outlet 11 c, avent outlet 11 d and a defroster outlet 11 e are provided in the secondend side of the air flow passage 11. The foot outlet 11 c is configuredto allow the air flowing through the air flow passage 11 to blow to thefeet of the passengers in the vehicle. The vent outlet 11 d isconfigured to allow the air flowing through the air flow passage 11 toblow to the upper bodies of the passengers in the vehicle. The defrosteroutlet 11 e is configured to allow the air flowing through the air flowpassage 11 to blow to the interior surface of the front window.

An indoor fan 12 such as a sirocco fan configured to allow the air toflow through the air flow passage 11 from end to end is provided in thefirst end side of the air flow passage 11. This indoor fan 12 is drivenby the electric motor 12 a.

Also, in the first end side of the air flow passage 11, an inletswitching damper 13 configured to open one of the outdoor air inlet 11 aand the indoor air inlet 11 b and to close the other. This inletswitching damper 13 is driven by the electric motor 13 a. When the inletswitching damper 13 closes the indoor air inlet 11 b and opens theoutdoor air inlet 11 a, the mode is switched to an outdoor air supplymode in which the airflows from the outdoor air inlet 11 a into the airflow passage 11. Meanwhile, when the inlet switching damper 13 closesthe outdoor air inlet 11 a and opens the indoor air inlet 11 b, the modeis switched to an indoor air circulation mode in which the air flowsfrom the indoor air inlet 11 b into the air flow passage 11. Moreover,when the inlet switching damper 13 is placed between the outdoor airinlet 11 a and the indoor air inlet 11 b and the outdoor air inlet 11 aand the indoor air inlet 11 b open, the mode is switched to a two-waymode in which the air flows from both the outdoor air inlet 11 a and theindoor air inlet 11 b into the air flow passage 11 according to theopening ratio of the outdoor air inlet 11 a and the indoor air inlet 11b.

Outlet switching dampers 13 b, 13 c and 13 d configured to open andclose the foot outlet 11 c, the vent outlet 11 d and the defrosteroutlet 11 e are provided in the foot outlet 11 c, the vent outlet 11 dand the defroster outlet 11 e, respectively, in the second side of theair flow passage 11. These outlet switching dampers 13 b, 13 c and 13 dare configured to move together by a linkage and are opened and closedby the electric motor 13 e. Here, when the outlet switching dampers 13b, 13 c and 13 d open the foot outlet 1 c, close the bent outlet 11 dand slightly open the defroster outlet 11 e, most of the air flowingthrough the air flow passage 11 blows out of the foot outlet 11 c andthe remaining air blows out of the defroster outlet 11 e. This mode isreferred to as “foot mode.” Meanwhile, when the outlet switching dampers13 b, 13 c and 13 d close the foot outlet 11 c and the defroster outlet11 e, and open the vent outlet 11 d, all the air flowing through the airflow passage 11 blows out of the vent outlet 11 d. This mode is referredto as “vent mode.” In addition, when the outlet switching dampers 13 b,13 c and 13 d open the foot outlet 11 c and the vent outlet 11 d, andclose the defroster outlet 11 e, the air flowing through the air flowpassage 11 blows out of the foot outlet 11 c and the vent outlet 11 d.This mode is referred to as “bi-level mode.” Moreover, when the outletswitching dampers 13 b, 13 c and 13 d close the foot outlet 11 c and thevent outlet 11 d, and open the defroster outlet 11 e, the air flowingthrough the air flow passage 11 blows out of the defroster outlet 11 e.This mode is referred to as “defroster mode.” Furthermore, when theoutlet switching dampers 13 b, 13 c and 13 d close the vent outlet 11 dand open the foot outlet 11 c and the defroster outlet 11 e, the airflowing through the air flow passage 11 blows out of the foot outlet 11c and the defroster outlet 11 e. This mode is referred to as“defroster-foot mode.” Here, in the bi-level mode, the air flow passage11, the foot outlet 11 c, the vent outlet 11 d, and a heat exchanger anda radiator which will be described later, are arranged and configuredsuch that the temperature of the air blowing out of the foot outlet 11 cis higher than the temperature of the air blowing out of the vent outlet11 d.

A heat exchanger 14 is provided in the air flow passage 11 in thedownstream of the air flow from the indoor fan 12. The heat exchanger 14is configured to cool and dehumidify the air flowing through the airflow passage 11. In addition, a radiator 15 is provided in the air flowpassage 11 in the downstream of the air flow from the heat exchanger 14.The radiator 15 is configured to heat the air flowing through the airflow passage 11. The heat exchanger 14 is a heat exchanger that isconstituted by fins and tubes and that is configured to perform heatexchange between the refrigerant flowing through the refrigerant circuit20 and the air flowing through the air flow passage 11. Meanwhile, theradiator 15 is a heat exchanger that is constituted by fins and tubesand that is configured to perform heat exchange between the waterflowing through the water circuit 30 and the air flowing through the airflow circuit 11.

An air mix damper 16 is provided between the heat exchanger 14 and theradiator 15 in the air flow passage 11 and is configured to control thepercentage of the air to be heated, which is flowing through the airflow passage 11. The air mix damper 16 is driven by the electric motor16 a. When the air mix damper 16 is disposed in the air flow passage 11in the upstream of the radiator 15, the percentage of the air subjectedto a heat exchange in the radiator 15 is reduced. Meanwhile, when theair mix damper 16 is moved to a position other than the radiator 15 inthe air flow passage 11, the percentage of the air subjected to a heatexchange is increased. In the air flow passage 11, when the air mixdamper 16 closes the upstream side of the radiator 15 and opens theportion other than the radiator 15, the opening degree is 0%, and, onthe other hand, when the air mix damper 16 opens the upstream side ofthe radiator 15 and closes the portion other than the radiator 15, theopening degree is 100%.

The refrigerant circuit 20 includes: the heat exchanger 14; a compressor21 configured to compress refrigerant; a water-refrigerant heatexchanger 22 configured to perform a heat exchange between therefrigerant and the water flowing through the water circuit 30; anoutdoor heat exchanger 23 configured to perform a heat exchange betweenthe refrigerant and the outdoor air; an indoor heat exchanger 24configured to perform a heat exchange between the refrigerant flowinginto the heat exchanger 14 and the refrigerant flowing out of the heatexchanger 14; a three-way valve 25 configured to switch the passage ofthe refrigerant; first to fourth solenoid valves 26 a to 26 d; first andsecond check valves 27 a and 27 b; and first and second expansion valves28 a and 28 b configured to decompress the refrigerant. These componentsare connected to each other by a copper pipe or an aluminum pipe. Thecompressor 21 and the outdoor heat exchanger 23 are disposed outside thevehicle interior. The compressor 21 is driven by the electric motor 21a. The outdoor heat exchanger 23 is provided with an outdoor fan 29configured to perform heat exchange between the outdoor air and therefrigerant when the vehicle stops. The outdoor fan 29 is driven by theelectric motor 29 a.

To be more specific, one side of the water-refrigerant heat exchanger 22into which the refrigerant flows is connected to one side of thecompressor 21 from which the refrigerant is discharged to form therefrigerant flow passage 20 a. In addition, the input side of theoutdoor heat exchanger 23 into which the refrigerant flows is connectedto the output side of the water-refrigerant heat exchanger 22 from whichthe refrigerant is discharged, thereby to form the refrigerant flowpassage 20 b. The refrigerant flow passage 20 b is provided with thethree-way valve 25. The one side of the three-way valve 25 from whichthe refrigerant is discharged and another side from which therefrigerant is discharged are parallel to one another and are connectedto the input side of the outdoor heat exchanger 23 into which therefrigerant flows and thereby to form the refrigerant flow passages 20 cand 20 d. The refrigerant flow passage 20 d is provided with the firstexpansion valve 28 a and the first check valve 27 a in the order fromthe upstream of the flow of the refrigerant. The input side of thecompressor 21 into which the refrigerant is sucked and the part of therefrigerant flow passage 20 d between the three-way valve 25 and thefirst expansion valve 28 a are connected in parallel to the output sideof the outdoor heat exchanger 23 from which the refrigerant isdischarged, thereby to form the refrigerant flow passage 20 e and 20 f.The refrigerant flow passage 20 e is provided with the first solenoidvalve 26 a. The refrigerant flow passage 20 f is provided with thesecond solenoid valve 26 b and the second check valve 27 b in the orderfrom the upstream of the flow of the refrigerant. The input side of theinterior heat exchanger 24 into which high-pressure refrigerant flows isconnected to the part of the refrigerant flow passage 20 d between thethree-way valve 25 and the first expansion valve 28 a, thereby to formthe refrigerant flow passage 20 g. The refrigerant passage 20 g isprovided with the third solenoid valve 26 c. One side of the heatexchanger 14 into which the refrigerant flows is connected to one sideof the interior heat exchanger 24 from which the high-pressurerefrigerant flows to provide the refrigerant flow passage 20 h. Therefrigerant flow passage 20 h is provided with the second expansionvalve 28 b. The input side of the indoor heat exchanger 24 into whichlow-pressure refrigerant flows is connected to the output side of theheat exchanger 14 from which the refrigerant is discharged, thereby toform the refrigerant flow passage 20 i. The part of the refrigerant flowpassage 20 e between the first solenoid valve 26 a and the input side ofthe compressor 21 into which the refrigerant is sucked is connected tothe output side of the indoor heat exchanger 24 from which thelow-pressure refrigerant is discharged, thereby to provide therefrigerant flow passage 20 j. The input side of the outdoor heatexchanger 23 into which the refrigerant flows is connected to therefrigerant flow passage 20 a, thereby to provide the refrigerant flowpassage 20 k. The refrigerant flow passage 20 k is provided with thefourth solenoid valve 26 d.

The water circuit 30 includes the radiator 15, the water-refrigerantheat exchanger 22, a pump 31 configured to pump the water as heat mediumand a water heater 32 as a heat medium heater, such as an electricheater configured to heat water by electric power. These components areconnected by a copper pipe or an aluminum pipe. To be more specific, theinput side of the water-refrigerant heat exchanger 22 into which waterflows is connected to output side of the pump 31 from which the water isdischarged, thereby to forma water flow passage 30 a. The input side ofthe water heater 32 into which the water flows is connected to theoutput side of the water-refrigerant heat exchanger 22 from which thewater is discharged, thereby to from a water flow passage 30 b. Theinput side of the radiator 15 into which the water flows is connected tothe output side of the water heater 32 from which the water isdischarged, thereby to form a water flow passage 30 c. The input side ofthe pump 31 into which the water is sucked is connected to the outputside of the radiator 15 from which the water flows, thereby to from awater flow passage 30 d. The pump 31 is driven by the electric motor 31a.

The vehicle air conditioning apparatus also includes a controller 40that controls the temperature and the humidity of the vehicle interiorto be the preset temperature and humidity.

The controller 40 includes a CPU, a ROM and a RAM. In the controller,upon receiving an input signal from a device connected to the inputside, the CPU reads the program stored in the ROM according to the inputsignal, stores the state detected by the input signal on the RAM andtransmits an output signal to a device connected to the output side.

As shown in FIG. 11, an electric motor 12 a for driving the indoor fan12; an electric motor 13 a for driving the inlet switching damper 13; anelectric motor 13 e for driving the outlet switching dampers 13 b, 13 cand 13 d; an electric motor 16 e for driving the air mix damper 16; anelectric motor 21 e for driving the compressor 21; the three-way valve25; the first to fourth solenoid valves 26 a, 26 b, 26 c and 26 d; anelectric motor 29 a for driving the outdoor fan 29; an electric motor 31a for driving the pump 31; and the water heater 32 are connected to theoutput side of the controller 40.

As shown in FIG. 11, an outdoor air temperature sensor 41 configured todetect temperature Tam outside the vehicle interior; an indoor airtemperature sensor 42 configured to detect temperature Tr in the vehicleinterior; an intake temperature sensor 43 configured to detecttemperature Ti of the air flowing into the air flow passage 11; a cooledair temperature sensor 44 configured to detect temperature Te of the airhaving been cooled in the heat exchanger 14; a heated air temperaturesensor 45 configured to detect temperature Tc of the air having beenheated in the radiator 15; an indoor air humidity sensor 46 configuredto detect humidity Th in the vehicle interior; a refrigerant temperaturesensor 47 configured to detect temperature Thex of the refrigerant afterthe heat exchange in the outdoor heat exchanger 23; an insolation sensor48 such as a photo sensor configured to detect amount of insolation Ts;a velocity sensor 49 configured to detect velocity V of the vehicle; anoperation part 50 configured to set modes regarding to target settingtemperature Tset and the switching of the operation; a pressure sensor51 configured to detect pressure Pd in the high-pressure side of therefrigerant circuit 20; and an outdoor air humidity sensor 53 configuredto detect humidity Rham outside the vehicle interior are connected tothe input side of the controller 40.

The vehicle air conditioning apparatus having the above-describedconfiguration performs cooling operation, cooling and dehumidifyingoperation, heating operation, first heating and dehumidifying operation,second heating and dehumidifying operation and defrost operation. Now,each operation will be explained.

First, the cooling operation will be explained. In the refrigerantcircuit 20, the flow passage of three-way valve is set to therefrigerant flow passage 20 c side; the second and third solenoid valves26 b and 26 c open and the first and fourth solenoid valves 26 a and 26d are closed; and the compressor 21 is operated. Meanwhile, theoperation of the pump 31 is stopped in the water circuit 30.

By this means, as shown in FIG. 12, the refrigerant discharged from thecompressor 21 flows through in this order: the refrigerant flow passage20 a; the water-refrigerant heat exchanger 22; water-refrigerant flowpassages 20 b and 20 c; the outdoor heat exchanger 23, the refrigerantflow passages 20 f, 20 d and 20 g, the high-pressure side of theinternal heat exchanger 24; the refrigerant flow passage 20 h; the heatexchanger 14; the refrigerant flow passage 20 i; the low-pressure sideof the internal heat exchanger 24; and the refrigerant flow passages 20j and 20 e, and is sucked into the compressor 21. The refrigerantflowing through the refrigerant circuit 20 releases the heat in theoutdoor heat exchanger 23 and absorbs the heat in the heat exchanger 14.Since the pump 31 is stopped in the cooling operation, heat is notreleased from refrigerant in the water-refrigerant heat exchanger 22.

In this case, in the air conditioning unit 10 during the coolingoperation, the indoor fan 12 is operated to flow the air through the airflow passage 11, and the air is subjected to a heat exchange with therefrigerant in the heat exchanger 14 and cooled. The temperature of thecooled air is the target air-blowing temperature TAO of the air to blowout of the outlets 11 c, 11 d and 11 e in order to set the temperatureof the vehicle interior to target setting temperature Tset. Then, theair at temperature Tset blows to the vehicle interior.

Next, the cooling and dehumidifying operation will be explained. In therefrigerant circuit 20, like the cooling operation, the flow passage ofthe three-way valve 25 is set to the refrigerant flow passage 20 c side;the second and third solenoid valves 26 b and 26 c open and the firstand fourth solenoid valves 26 a and 26 d are closed; and the compressor21 is operated. In the water circuit 30, the pump 31 is operated.

By this means, as shown in FIG. 3, the refrigerant discharged from thecompressor 21 flows through in the same way as in the cooling operation.The refrigerant flowing through the refrigerant circuit 20 releases theheat in the water-refrigerant heat exchanger 22 and the outdoor heatexchanger 23, and absorbs the heat in the heat exchanger 14.

In addition, the water discharged from the pump 31 flows through in thisorder: the water-refrigerant heat exchanger 22, the water heater 32; andthe radiator 15 as indicated by the chain line of FIG. 12, and is suckedinto the pump 31. The water flowing through the water circuit 30 absorbsthe heat in the water-refrigerant heat exchanger 22 and releases theheat in the radiator 15.

At this time, in the air conditioning unit 10 during the cooling anddehumidifying operation, the indoor fan 12 is operated to flow the airthrough the air flow passage 11, and the air is subjected to a heatexchange with the refrigerant which absorbs the heat in the heatexchanger 14, and therefore is cooled and dehumidified. The air havingbeen dehumidified in the heat exchanger 14 is subject to heat exchangewith the water which releases the heat in the radiator 15, and thereforeheated. As a result, the air at the target air-blowing temperature TAOblows to the vehicle interior.

Next, the heating operation will be explained. In the refrigerantcircuit 20, the flow passage of the three-way valve 25 is set to therefrigerant flow passage 20 d side; the first solenoid valve 26 a opensand the second to fourth solenoid valves 26 b to 26 d are closed: andthe compressor 21 is operated. In the water circuit 30, the pump 31 isoperated.

By this means, as shown in FIG. 13, the refrigerant discharged from thecompressor 21 flows through this order: the refrigerant flow passage 20a; the water-refrigerant heat exchanger 22; the refrigerant flowpassages 20 b and 20 d; the outdoor heat exchanger 23; and therefrigerant flow passage 20 e, and is sucked into the compressor 21. Therefrigerant flowing through the refrigerant circuit 20 releases the heatin the water-refrigerant heat exchanger 22 and absorbs the heat in theoutdoor heat exchanger 23.

Meanwhile, as shown in FIG. 13, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22;the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22 and releases the heat in theradiator 15.

In this case, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11, and theflowing air is not subject to a heat exchange with the refrigerant inthe heat exchanger 14, but is subjected to a heat exchange with thewater in the radiator 15 and therefore is heated. As a result, the airat the target air-blowing temperature TAO blows to the vehicle interior.

Next, the first heating and dehumidifying operation will be explained.In the refrigerant circuit 20, the flow passage of the three-way valve25 is set to the refrigerant flow passage 20 d side; the first and thirdsolenoid valves 26 a and 26 c open and the second and fourth solenoidvalves 26 b and 26 d are closed; and the compressor 21 is operated.Meanwhile, the pump 31 is operated in the water circuit 30.

By this means, as shown in FIG. 14, the refrigerant discharged from thecompressor 21 flows through in this order: the refrigerant flow passage20 a; the water-refrigerant heat exchanger 22; and the refrigerant flowpassages 20 b and 20 d. Part of the refrigerant flowing through therefrigerant flow passage 20 d flows through in this order: the outdoorheat exchanger 23; and the refrigerant flow passage 20 e, and is suckedinto the compressor 21. In addition, remaining refrigerant flowingthrough the refrigerant flow passage 20 d flows through in this order:the refrigerant flow passage 20 g; the high-pressure side of theinterior heat exchanger 24; the refrigerant flow passage 20 h; the heatexchanger 14; the refrigerant flow passage 20 i; the low-pressure sideof the interior heat exchanger 24; and the refrigerant flow passages 20j and 20 e, and is sucked into the compressor 21. The refrigerantflowing through the refrigerant circuit 20 releases the heat in thewater-refrigerant heat exchanger 22 and absorbs the heat in the heatexchanger 14 and the outdoor heat exchanger 23.

Meanwhile, as shown in FIG. 14, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22;the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22 and releases the heat from theradiator 15.

At this time, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11, and theflowing air is subjected to a heat exchange with the refrigerant in theheat exchanger 14, and therefore is cooled and dehumidified. Part of theair having been dehumidified in the heat exchanger 14 is subjected to aheat exchange with the water in the radiator 15 and heated. As a result,the air at the target air-blowing temperature TAO blows into the vehicleinterior.

Next, the second heating and dehumidifying operation will be explained.In the refrigerant circuit 20, the flow passage of the three-way valve25 is set to the refrigerant flow passage side 20 d; the third solenoidvalve 26 c opens and the first, second and fourth solenoid valves 26 a,26 b and 26 d are closed; and the compressor 21 is operated. Meanwhile,the pump 31 is operated in the water circuit 30.

By this means, as shown in FIG. 15, the refrigerant discharged from thecompressor 21 flows through in this order: the refrigerant flow passage20 a; the water-refrigerant heat exchanger 22; the refrigerant flowpassages 20 b, 20 d and 20 g; the high-pressure side of the interiorheat exchanger 24; the refrigerant flow passage 20 h; the heat exchanger14; the refrigerant flow passage 20 i; the low-pressure side of theinterior heat exchanger 24; and the refrigerant flow passages 20 j and20 e, and is sucked into the compressor 21. The refrigerant flowingthrough the refrigerant circuit 20 releases the heat in thewater-refrigerant heat exchanger 22 and absorbs the heat in the heatexchanger 14.

Meanwhile, as shown in FIG. 15, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22;the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22 and releases the heat in theradiator 15.

At this time, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11, and theflowing air is subjected to a heat exchange with the refrigerant in theheat exchanger 14, and therefore is cooled and dehumidified in the sameway as in the first heating and dehumidifying operation. Part of the airdehumidified in the heat exchanger 14 is subjected to a heat exchangewith the water in the radiator 15, and therefore heated. As a result,the air at the target air-blowing temperature TAO blows to the vehicleinterior.

Next, the defrost operation will be explained. In the refrigerantcircuit 20, the flow passage of the three-way valve 25 is set to therefrigerant flow passage 20 d side; the first and fourth solenoid valves26 a and 26 d open and the second and third solenoid valves 26 d and 26c are closed; and the compressor 21 is operated. Meanwhile, the pump 31is operated in the water circuit 30.

By this means, as shown in FIG. 16, part of the refrigerant dischargedfrom the compressor 21 flows through in this order: the refrigerant flowpassage 20 a; the water-refrigerant heat exchanger 22; the refrigerantflow passages 20 b and 20, and flows into the outdoor heat exchanger 23.In addition, the remaining refrigerant discharged from the compressor 21flows through the refrigerant flow passages 20 a and 20 k and flows intothe outdoor heat exchanger 23. The refrigerant flowing out of theoutdoor heat exchanger 23 flows through the refrigerant flow passage 20e, and is sucked into the compressor 21. The refrigerant flowing throughthe refrigerant circuit 20 releases the heat in the radiator 15, and atthis time, absorbs the heat in the outdoor heat exchanger 23.

Meanwhile, as shown in FIG. 16, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22,the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22, and releases the heat in theradiator 15.

In this case, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11. The flowingair is not subjected to a heat exchange with the refrigerant in the heatexchanger 14, but is subjected to a heat exchange with the water whichreleases the heat in the radiator 15, and therefore is heated and thenblows to the vehicle interior.

While the automatic switch of the operation part 50 is turned on, thecontroller 40 performs an operation switching control process to switchamong the cooling operation, the cooling and dehumidifying operation,the heating operation, the first heating and dehumidifying operation,the second heating and dehumidifying operation, and the defrostoperation, based on indoor and outdoor environmental conditions, such astemperature.

In each operation switched by the operation switching control process,the controller 40 switches among the foot mode, the vent mode and thebi-level mode according to the target air-blowing temperature TAO. To bemore specific, when the target air-blowing temperature TAO is high, forexample, 40 degrees centigrade, the controller 40 sets the foot mode.Meanwhile, when the target air-blowing temperature TAO is low, forexample, lower than 25 degrees centigrade, the controller sets the ventmode. Moreover, when the target air-blowing temperature TAO is thetemperature between the temperature for the foot mode and thetemperature for the vent mode, the controller 40 sets the bi-level mode.

The controller 40 switches the mode of the outlets 11 c, 11 d and 11 eby using the outlet switching dampers 13 b, 13 c and 13 d, and controlsthe opening degree of the air mix damper 16 in order to set thetemperature of the air blowing out of the outlets 11 c, 11 d, and 11 eto the target air-blowing temperature TAO.

In addition, during the heating operation or the heating anddehumidifying operation, the controller 40 performs a water temperaturecontrol process to control the temperature of the water flowing throughthe water circuit 30 to be the temperature that realizes the quantity ofheating for the target air-blowing temperature TAO. The operation of thecontroller 40 for this process will be explained with reference to theflowchart shown in FIG. 17.

(Step S31)

In step S31, the CPU calculates the target air-blowing temperature TAOand moves the step to step S32. The target air-blowing temperature TAOis calculated based on the preset temperature Tset, and environmentalconditions such as the outdoor air temperature Tam, the indoor airtemperature Tr, and an amount of insolation Ts. The environmentalconditions are detected by the outdoor air temperature sensor 41, theindoor air temperature sensor 42, the insolation sensor 44 and so forth.

(Step S32)

In step S32, the CPU calculate target water temperature TG_TW, which isthe temperature of the water to be flowed into the radiator 15 torealize the quantity of heating to make the temperature of the airblowing from the outlets 11 c, 11 d and 11 e the target air-blowingtemperature TAO, and moves the step to step S33. The target watertemperature TG_TW is calculated based on the target air-blowingtemperature TAO calculated in the step S31, the temperature Te of theair having been cooled in the heat exchanger 14 (in case of the heatingoperation, the temperature Ti of the air flowing into the air flowpassage 11), and temperature efficiency ratio φwof the air to the water(TG_TW=(TAO−Te)/φw+Te).

(Step S33)

In step S33, the CPU calculates temperature Tco of the refrigeranthaving released the heat in the water-refrigerant heat exchanger 22, andmoves the step to step S34. The temperature Tco is calculated based onpressure Pd of the refrigerant circuit 20 in the high-pressure side,heat efficiency φk of the water to the refrigerant in thewater-refrigerant heat exchanger 22 (Tco=FuncTco(Pd,φk), where FuncTcois a function to calculate the temperature Tco).

(Step S34)

In step S34, the CPU calculates estimated water temperature TWhp of thewater in the water circuit 30 having heated by the water-refrigerantheat exchanger 22, and moves the step to step S35. The estimated watertemperature TWhp is calculated based on the temperature Tco of therefrigerant having released the heat in the water-refrigerant heatexchanger 22, the temperature efficiency allowing for the flow rate Gwof the water flowing through the water circuit 30 (TWhp=GSw(Tco×φ(Gw)),where GSw is a function to calculate the estimated water temperatureWhp, allowing for the response lag of the temperature of the waterflowing through the water circuit).

(Step S35)

In step S35, the CPU calculates estimated pressure Ps of the compressor21 in the inlet side, and moves the step to step S36. The estimatedpressure Ps of the compressor 21 in the inlet side is calculated basedon the outdoor air temperature Tam, the number of rotations Nc of thecompressor 21 and the pressure Pd of the refrigerant circuit 20 in thehigh-pressure side (Ps=FuncPs (Tam, Nc, Pd), where FuncPs is a functionto calculate the estimated pressure Ps.

(Step S36)

In the step S36, the CPU performs a quantity-of-heating control processto control the quantity of heating of the water flowing through thewater circuit 30, based on the estimated water temperature TWhp acquiredin the step S4 and the estimated pressure Ps acquired in the step S35,and ends the water temperature control process. This quantity-of-heatingcontrol process will be explained later with reference to FIG. 18.

Now, the quantity-of-heating control process will be explained withreference to FIG. 18.

(Step S41)

In step S41, the CPU determines whether or not the estimated pressure Psof the compressor 21 in the inlet side is predetermined pressure P1 orhigher. When determining that the estimated pressure Ps is thepredetermined pressure P1 or higher, the CPU moves the step to step S45.On the other hand, when determining that the estimated pressure Ps islower than the predetermined pressure P1, the CPU moves the step to stepS42. Here, the predetermined pressure P1 is set to, for example, 1013.25hPa as the standard pressure in order to prevent the compressor 21 frombeing damaged.

(Step S42)

When the estimated pressure Ps is lower than the predetermined pressureP1 in the step S41, the CPU, in the step S42, controls the number ofrotations Nc of the compressor 21 to make the estimated pressure Ps atleast the predetermined pressure P1 or higher, and moves the step tostep S43.

(step S43)

In the step S43, the CPU determines whether the number of rotations ofthe compressor 21 is predetermined number of rotations N1 or lower. Whendetermining that the number of rotations Nc is the predetermined numberof rotations N1 or lower, the CPU moves the step to step S44. On theother hand, when determining that the number of rotations Nc is higherthan the predetermined number of rotations N1, the CPU moves the step tostep S45.

(Step S44)

When determining that the number of rotations Nc is the predeterminednumber of rotations N1 or lower in the step S43, the CPU, in the step44, stops the compressor 21 from driving, and moves the step to step theS45.

(Step S45)

When determining that the estimated pressure Ps is the predeterminedpressure P1 or higher in the step S41, when determining that the numberof rotations Nc is higher than the predetermined number of rotations N1in the step S43, or when the compressor 21 is stopped from driving inthe step S44, the CPU performs a water heater control process to controlthe operation of the water heater 32, and ends the quantity-of-heatingcontrol process. This water heater control process will be explainedwith reference to FIG. 19.

Now, the water heater control process will be explained.

(Step S51)

In step S51, the CPU determines whether or not numerical value(TG_TW−TWhp) obtained by subtracting the estimated water temperatureTWhp from the target water temperature TG_TW is predetermined value T1or higher. When the numerical value (TG_TW−TWhp) is the predeterminedvalue T1 or higher, the CPU moves the step to step S52. On the otherhand, when the numerical value (TG_TW−TWhp) is lower than thepredetermined value T1, the CPU moves the step to step S55.

(Step S52)

When the numerical value (TG_TW−TWhp) is the predetermined value T1 orhigher in the step S51, the CPU, in the step S52, calculates targetquantity-of-heat generation TG_Qhtr that the water heater 32 shouldapply to the water in the water circuit 30, and moves the step to stepS53. The target quantity-of-heat generation TG_Qhtr is an output valueof the proportional control, which is calculated based on the targetwater temperature TG_TW, the estimated water temperature TWhp, thespecific heat Cpw of the water, the water density ρw, and the flow rateGw of the water flowing through the water heater 32. The flow rate Gw ofthe water can be estimated based on the current value to drive the pump31.

(Step S53)

In the step S53, the CPU calculates the target power TG_Whtr thatcorresponds to the target quality-of heat generation TG_Qhtr in thewater heater 32, and moves the step to the step S54. The target powerTG_Whtr is calculated based on the target quantity-of-heat generationTG_Qhtr calculated in the step S52 and heat generation efficiencyEFF_htr of the water heater 32 (TG_Whtr=TG_Qhtr×(1/EFF_htr)).

(Step S54)

In the step S54, the CPU operates the water heater 32 at the targetpower TG_Whtr calculated in the step S53, and ends the water heatercontrol process.

(Step S55)

When the numerical value (TG_TW−TWhp) is lower than the predeterminedvalue T1 in the step S51, the CPU stops the water heater 32 in step S5,and ends the water heater control process.

In addition, during the first heating and dehumidifying operation andduring the second heating and dehumidifying operation, the controller 40performs an operation switching control process to switch the operationto the cooling and dehumidifying when the air conditioning apparatuslacks in dehumidifying capability. This operation switching controlprocess will be explained with reference to FIG. 20.

(Step S61)

In step S61, the CPU determines whether the operation is the firstheating and dehumidifying operation or the second heating anddehumidifying. When determining that the operation is one of the firstheating and dehumidifying operation and the second heating anddehumidifying operation, the CPU moves the step to step S62. On theother hand, when determining that the operation is neither the firstheating and dehumidifying operation nor the second heating anddehumidifying operation, the CPU moves the operation to step S66.

When the operation is one of the first heating and dehumidifyingoperation and the second heating and dehumidifying operation In the stepS61, the CPU, in the step S62, calculates the required quantity ofdehumidification based on the indoor air temperature Tr and the outdoorhumidity Rh, and moves the step to step S63.

(Step S63)

In the step S63, the CPU calculates the dehumidifying capability in thefirst heating and dehumidifying operation and the second heating anddehumidifying operation, and moves the step to step S64.

(Step S64)

In the step S64, the CPU determines whether or not the dehumidifyingcapability calculated in the step S63 is the required quantity ofdehumidification calculated in the step S62 or higher. When determiningthat the dehumidifying capability is the required quantity ofdehumidification or higher, the CPU moves the step to step S66. On theother hand, when determining that the dehumidifying capability is lowerthan the required quantity of dehumidification, the CPU moves the stepto step S65.

(Step S65)

When determining that the dehumidifying capability is not the requiredquantity of dehumidification or higher in the step S64, the CPU, in thestep S65, switches one of the first heating and dehumidifying operationand the second heating and dehumidifying operation to the cooling anddehumidifying operation, and moves the step to step S66.

(Step S66)

When determining that the operation is neither the first heating anddehumidifying operation nor the second heating and dehumidifyingoperation in the step S61, or when the operation is switched to thecooling and dehumidifying operation in the step S65, the CPU, in thestep S66, performs the above-described quantity-of-heating controlprocess shown in FIG. 18, and ends the operation switching controlprocess.

In addition, the controller 40 determines whether or not a frost isformed on the outdoor heat exchanger 23, and performs a defrostoperation control process when a frost is formed on the outdoor heatexchanger 23. Now, the defrost operation control process will beexplained with reference to FIG. 21.

(Step S71)

In step S71, the CPU calculates outdoor air dew point temperature Tdewbased on the outdoor air temperature Tam detected by the outdoor airtemperature sensor 41 and outdoor humidity Rham detected by the outdoorhumidity sensor 53.

(Step S72)

In step S72, the CPU determines whether or not the temperature Thex ofthe refrigerant flowing out of the outdoor heat exchanger 23, which isdetected by the refrigerant temperature sensor 47, is lower than theoutdoor air dew point temperature Tdew. When determining that thetemperature Thex of the refrigerant is lower than the outdoor air dewpoint temperature Tdew, the CPU moves the step to step S73. On the otherhand, when determining that the temperature Thex of the refrigerant isnot lower than the outdoor air dew point temperature Tdew, the CPU endsthe defrost operation control process.

(Step S73)

In the step S73, when determining that the outdoor air dew pointtemperature Tdew is lower than the temperature Thex of the refrigerant,the CPU performs the above-described defrost operation for apredetermined period of time, and ends the defrost operation controlprocess.

Next, when the heat exchanger 15 does not release sufficient heat in thedefrost operation, the CPU performs a heat release compensation controlprocess to compensate for a lack in the quantity of heat release. Now,the heat release compensation control process will be explained withreference to FIG. 22.

(Step S81)

In step S81, the CPU determines whether or not the operation is thedefrost operation. When determining that the operation is the defrostoperation, the CPU moves the step to step S82. On the other hand, whendetermining that the operation is not the defrost operation, the CPUmoves the step to step S88.

(Step S82)

When determining that the operation is the defrost operation in the stepS81, the CPU determines whether or not the elapsed period of time afterthe operation is switched to the defrost operation falls within apredetermined period of time in the step S82. When determining that theelapsed period of time after the operation is switched to the defrostoperation falls within the predetermined period of time, the CPU movesthe step to step S85.

(Step S83)

When determining that the elapsed period of time after the operation isswitched to the defrost operation falls within the present period oftime in the step S82, the CPU, in the step S83, stores the quantity ofheat release Qhp_htrof the water-refrigerant heat exchanger 22 justbefore the operation is switched to the defrost operation on the RAM,and moves the step to step S84 (the quantity of heat release stored inthe RAM is represented as “Qhp_htr_mem”).

(Step S84)

In the step S84, the CPU stores the target quantity-of-heat generationTG_Qhtr of the water heater 32 just before the operation is switched tothe defrost operation on the RAM, and moves the operation to step S85(the quantity of heat release stored in the RAM is represented as“TG_Qhtr_mem”).

(Step S85)

When determining that the elapsed period of time after the operation isswitched to the defrost operation does not fall within the predeterminedperiod of time in the step S82, or when determining that the targetquantity-of-heat generation TG_Qhtr of the water heater 32 is stored onthe RAM in the step S84, the CPU, in the step S85, calculates decreasedquantity of heat release Qhp_dec of the water-refrigerant heat exchanger22, and moves the step to step S86. The decreased quantity of heatrelease Qhp_dec is calculated by subtracting the current quantity ofheat release Qhp_htr of the water-refrigerant heat exchanger 22 from thequantity of heat release Qhp_htr_mem of the water-refrigerant heatexchanger 22 just before the operation is switched to the defrostoperation, which is stored in the step S83(Qhp_dec=Qhp_htr_mem−Qhp_htr).

(Step S86)

In step S86, the CPU calculates the target power TG_Whtr of the waterheater 32, and moves the step to step S87. The target power TG_Whtr iscalculated based on the quantity of heat release Qhp_htr_mem stored onthe RAM in the step S83, the decreased quantity of heat release Qhp_deccalculated in the step S85, and the heat generation efficiency EFF_htrof the water heater 32 (TG_Whtr=(Qhtr_mem−Qhp_dec)×(1/EFF_htr)).

(Step S87)

In step S87, the CPU operates the water heater 32 at the target powerTG_Whtr calculated in the step S86, and ends the quantity of heatrelease compensation control process.

(Step S88)

When determining that the operation is not the defrost operation in thestep S81, the CPU performs the quantity-of-heating control process shownin FIG. 18 in step S88, and ends the quantity-of-heating compensationcontrol process.

As described above, the vehicle air conditioning apparatus according tothe present embodiment estimates the temperature of the water flowingthrough the water circuit 30, which has been heated in thewater-refrigerant heat exchanger 22; calculates the insufficientquantity of heat during the heating operation or during the heating anddehumidifying operation, based on the estimated water temperature TWhpof the water flowing through the water circuit 30; and controls thewater heater 32 based on the calculated insufficient quantity of heatTG_Qhtr. By this means, only the insufficient quantity of heat releasein the water-refrigerant heat exchanger 22 is compensated by operatingthe water heater 32. Therefore, it is possible to minimize the operationof the water heater 32, and consequently reduce the power consumptionfor driving the vehicle. As a result, it is possible to prevent themileage of the vehicle from dropping.

In addition, the operation of the compressor 21 is controlled such thatthe estimated pressure Ps of the compressor 21 in the inlet side is atleast the predetermined pressure P1 or higher. By this means, it ispossible to prevent the pressure of the compressor 21 in the inlet sidefrom being lower than the predetermined pressure P1. Therefore, it ispossible to prevent the compressor 21 from failing.

In addition, when the number of rotations Nc of the compressor 21 is thepredetermined number of rotations N1, the operation of the compressor 21is stopped. By this means, it is possible to prevent the inefficientoperation due to a decrease in the number of rotations Nc of thecompressor 21.

In addition, the target water temperature TG_TW flowing through thewater circuit 30; The operation of the water heater 32 is resumed whenthe difference between the calculated target temperature TG_TW and theestimated water temperature TWhp of the water flowing through the watercircuit 30 is the predetermined value T1 or higher; and the operation ofthe water heater 32 is stopped when the difference between thecalculated target temperature TG_TW and the estimated water temperatureTWhp of the water flowing through the water circuit 30 is lower than thepredetermined value T1. By this means, when the water flowing throughthe water circuit 30 has a predetermined quantity of heat, the operationof the water heater 32 is stopped. Therefore, it is possible to preventthe unnecessary operation of the water heater 32.

Moreover, the required quantity of dehumidification based on thetemperature and the humidity of the vehicle interior; the possiblequantity of dehumidification that can be realized during the heating anddehumidifying operation; when the calculated possible quantity ofdehumidification is lower than the required quantity ofdehumidification, the operation is switched from the heating anddehumidifying operation to the cooling and dehumidifying operation;although the quantity of heat released from the water-refrigerant heatexchanger becomes insufficient due to the operation is switched from theheating and dehumidifying operation to the cooling and dehumidifyingoperation, the insufficient quantity of heat is compensated by the waterheater 32. By this means, even if the required quantity ofdehumidification is beyond the dehumidifying capability of the heatingand dehumidifying operation, it is possible to secure the requiredquantity of dehumidification and also to keep the temperature Tr of thevehicle interior at the indoor air temperature Tset. Therefore, it ispossible to maintain the environment of the vehicle interior in a goodcondition.

Moreover, during the defrost operation, the water heater 32 is operatedto heat the water flowing through the water circuit 30, and therefore tocontinue to heat the vehicle interior. By this means, it is possible tokeep the temperature Tr in the vehicle interior at the temperature Tsetduring the defrost operation, and therefore to maintain the environmentof the vehicle interior in a good condition.

When the temperature Thex of the refrigerant flowing out of the outdoorheat exchanger 23, which has been detected by the refrigeranttemperature sensor 47 is lower than the outdoor air dew pointtemperature Tdew, the defrost operation is performed. By this means, itis possible to reliably perform the defrost operation when a conditionin which a frost is formed on the outdoor heat exchanger 23 occurs, andtherefore to prevent the outdoor heat exchanger 23 from frosting.

FIG. 23 shows Embodiment 4 of the present invention. Here, the samecomponents are assigned the same reference numerals as in Embodiment 3.

In the vehicle air conditioning apparatus according to the presentembodiment, the controller 40 performs the quantity-of-heating controlprocess shown by the flowchart in FIG. 23 with the same configuration asin Embodiment 3.

(Step S91)

In step S91, the CPU determines whether or not the estimated pressure Psof the compressor 21 in the inlet side is predetermined pressure P1 orhigher. When determining that the estimated pressure Ps is thepredetermined pressure P1 or higher, the CPU moves the step to step S93.On the other hand, when determining that the estimated pressure Ps islower than the predetermined pressure P1, the CPU moves the step to stepS92. Here, like the above-described embodiment, the predeterminedpressure P1 is set to, for example, 1013.25 hPa as the standard pressurein order to prevent the compressor 21 from being damaged.

(Step S92)

When determining that the estimated pressure Ps is lower than thepredetermined pressure P1 in the step S91, the CPU, in step S92,controls the number of rotations Nc of the compressor 21 such that theestimated pressure Ps is not lower than predetermined pressure P2(P2<P1) in the step S92, and moves the step to step S93.

(Step S93)

When determining that the estimated pressure Ps is the predeterminedpressure P1 or higher in the step S91, or when controlling the number ofrotations Nc of the compressor 21 in the step S92, the CPU performs thewater heater control process in the same way as in thequantity-of-heating control process in Embodiment 3, and ends thequantity-of-heating control process.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, the operation of the compressor 21is controlled such that the estimated pressure Ps of the compressor 21in the inlet side is at least the predetermined pressure P1 or higher.By this means, it is possible to prevent the estimated pressure Ps ofthe compressor 21 in the inlet side from being lower than thepredetermined pressure P1, and therefore to prevent the compressor 21from failing, like Embodiment 3.

FIG. 24 shows Embodiment 5 of the present invention. Here, the samecomponents are assigned the same reference numerals as in Embodiment 4.

In the vehicle air conditioning apparatus according to the presentembodiment, the controller 40 performs the quantity-of-heating controlprocess shown by the flowchart in FIG. 24 with the same configuration asin Embodiment 3.

(Step S101)

In step S101, the CPU calculates number of rotations LIM_Nc of thecompressor 21 such that the estimated pressure Ps of the compressor 21in the inlet side is the predetermined pressure P2, based on the outdoorair temperature Tam, and moves the step to step S102.

(Step S102)

In the step S102, the CPU determines whether or not the number ofrotations LIM_Nc of the compressor 21 is higher than the predeterminednumber of rotations N2N1. When the number of rotations LIM_Nc is higherthan the predetermined number of rotations N1, the CPU moves the step tostep S103. On the other hand, when the number of rotations LIM_Nc is thepredetermined number of rotations N1 or lower, the CPU moves the step tostep S104.

(Step S103)

When determining that the number of rotations LIM_Nc is higher than thepredetermined number of rotations N1 in the step S102, the CPU, in thestep S103, controls the number of rotations of the compressor 21 to bethe number of rotations LIM_Nc, and moves the step to step S105

(Step S104)

When determining that the number of rotations LIM_Nc is thepredetermined number of rotations N1 or lower in the step S102, the CPU,in step 104, stops the operation of the compressor 21 and moves the stepto step S105.

(Step S105)

When controlling the number of rotations of the compressor 21 in thestep S103, or when stopping the operation of the compressor 21 in thestep S104, the CPU performs the water heater control process in the sameway as in the quantity-of-heating control process in Embodiment 3, andends the quantity-of-heating control process.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, the number of rotations LIM_Nc ofthe compressor 21 is calculated such that the estimated pressure Ps ofthe compressor 21 in the inlet side is the predetermined pressure P2,and the operation of the compressor 21 is controlled such that thecompressor 21 is operated at the calculated number of rotations LIM_Nc.By this means, it is possible to prevent the compressor 21 from failingbecause of a decrease in pressure of the compressor 21 in the inletside.

In addition, when the calculated number of rotations LMN_Nc is thepredetermined number of rotations N1 or lower, the operation of thecompressor 21 is stopped. By this means, it is possible to prevent theinefficient operation due to a decrease in the number of rotations Nc ofthe compressor 21.

FIG. 25 shows Embodiment 6 of the present invention. Here, the samecomponents are assigned the same reference numerals as in Embodiment 5.

In the vehicle air conditioning apparatus according to the presentembodiment, the controller 40 performs the quantity-of-heating controlprocess shown by the flowchart in FIG. 25 with the same configuration asin Embodiment 3.

(Step S111)

In step S111, the CPU calculates number of rotations LIM_Nc of thecompressor 21 such that the estimated pressure Ps of the compressor 21in the inlet side is the predetermined pressure P2, based on the outdoorair temperature Tam, and moves the step to step S112.

(Step S112)

In step S112, the CPU controls the number of rotations of the compressor21 to be the number of rotations LIM_Nc, and moves the step to stepS113.

(Step S113)

In step S113, the CPU performs the water heater control process in thesame way as in the quantity-of-heating control process according toEmbodiment 3, and ends the quantity-of-heating control process.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, the number of rotations LIM_Nc ofthe compressor 21 is calculated such that the estimated pressure Ps ofthe compressor 21 in the inlet side is the predetermined pressure P2,and the operation of the compressor 21 is controlled such that thecompressor 21 is operated at the calculated number of rotations LIM_Nc.By this means, it is possible to prevent the compressor 21 from failingdue to a decrease in pressure of the compressor 21 in the inlet side,like Embodiment 3.

FIG. 26 shows Embodiment 7 of the present invention. Here, the samecomponents are assigned the same reference numerals as in Embodiment 6.

In the vehicle air conditioning apparatus according to the presentembodiment, the controller 40 performs the water heater control processshown by the flowchart in FIG. 26 with the same configuration as inEmbodiment 3.

(Step S121)

In step S121, the CPU calculates the target quantity-of-heat generationTG_Qhtr that the water heater 32 should apply to the water in the watercircuit 30, and moves the step to step S122. The target quantity-of-heatgeneration TG_Qhtr is an output value of proportional-plus-integralcontrol, which is calculated based on the target water temperatureTG_TW, the estimated water temperature TWhp, the specific heat Cpw ofthe water, the water density ρw, and the flow rate Gw of the waterflowing through the water heater 32(TG_Qhtr=(P_GAIN×(TG_TW−TWhp)+I_GAIN×(TG_TW−TWhp)+I_Qhtrz)×Cpw×ρw×Gw,where P_GAIN is a constant value as proportional gain; I_GAIN is aconstant value as integral gain; and I_Qhtrz is the previous value ofI_Qhtr, I_Qhtr=I_GAIN×(TG_TW−TWhp)+I_Qhtrz).

(Step S122)

In step S122, the CPU calculates the target heat power TG_Whtr thatcorresponds to the target quantity-of-heat generation TG_Qhtr of thewater heater 32, and moves the step to step S123. The target powerTG_Whtr is calculated based on the target quantity-of-heat generationTG_Qhtr calculated in the step S121 and the heat generation efficiencyEFF_htr of the water heater 32 (TG_Whtr=TG_Qhtr×(1/EFF_htr)).

(Step S123)

In step S123, the CPU operates the water heater 32 at the target powerTG_Whtr calculated in the step S122, and ends the water heater controlprocess.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, it is possible to calculate thetarget quantity-of-heat generation TG_Qhtr of the water heater 32 in thesame way as in Embodiment 3.

FIG. 27 shows Embodiment 8 of the present invention. Here, the samecomponents are assigned the same reference numerals as in Embodiment 7.

In the vehicle air conditioning apparatus according to the presentembodiment, the controller 40 performs the water heater control processshown by the flowchart in FIG. 27 with the same configuration as inEmbodiment 3.

(Step S131)

In step S131, the CPU determines whether or not the numerical value(TG_TW−TWhp) obtained by subtracting the estimated water temperatureTWhp from the target water temperature TG_TW is lower than thepredetermined value T2. When the numerical value (TG_TW−TWhp) is lowerthan the predetermined value T2, the CPU moves the step to step S132. Onthe other hand, when the numerical value (TG_TW−TWhp) is thepredetermined value T2 or higher, the CPU moves the step to step S133.

(Step S132)

When determining that the numerical value (TG_TW−TWhp) is lower than thepredetermined value T2 in the step S131, the CPU, in the step S132,calculates the target quantity-of-heat generation TG_Qhtr that the waterheater 32 should apply to the water in the water circuit 30, and movesthe step to step S134. The target quantity-of-heat generation TG_Qhtr isan output value of proportional-plus-integral control, which iscalculated based on the target water temperature TG_TW, the estimatedwater temperature TWhp, the specific heat Cpw of the water, the waterdensity ρw, and the flow rate Gw of the water flowing through the waterheater 32(TG_Qhtr=(P_GAIN×(TG_TW−TWhp)+I_GAIN×(TG_TW−TWhp)+I_Qhtrz)×Cpw×ρw×Gw,where P_GAIN is a constant value as proportional gain; I_GAIN is aconstant value as integral gain; and I_Qhtrz is the previous value ofI_Qhtr, I_Qhtr=I_GAIN×(TG_TW−TWhp)+I_Qhtrz).

(Step S133)

When determining the numerical value (TG_TW−TWhp) is the predeterminedvalue T2 or higher in the step S131, the CPU sets the targetquantity-of-heat generation TG_Qhtr to maximum quantity of heating Q_maxin the step S133.

(Step S134)

When calculating the target quantity-of-heat generation TG_Qhtr in thestep S132, or when determining the target quantity-of-heat generationTG_Qhtr in the step S133, the CPU, in step S134, calculates the targetpower TG_Whtr that corresponds to the target quantity-of-heat generationTG_Qhtr of the water heater 32, and moves the step to step S135. Thetarget power TG_Whtr is calculated based on the target quantity-of-heatgeneration calculated in the step S132 and the heat generationefficiency EFF_htr of the water heater 32 (TG_Whtr=TG_Qhtr×(1/EFF_htr)).

(Step S135)

In step S135, the CPU operates the water heater 32 at the target powerTG_Whtr calculated in the step S134, and ends the water heater controlprocess.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, when the numerical value(TG_TW−TWhp) obtained by subtracting the estimated water temperatureTWhp from the target water temperature TG_TW is the predetermined valueT2 or higher water, the target quantity-of-heat generation TG_Qhtr isset to the maximum quantity of heating Q_max to operate the water heater32. By this means, it is possible to operate the water heater 32 at themaximum output just after the heating operation or the heating anddehumidifying operation is stated. Therefore, it is possible to rapidlyheat the vehicle interior to a comfortable temperature.

Here, with the present embodiment, a configuration has been describedwhere the heat released from the water-refrigerant circuit 20 isabsorbed in the water flowing through the water circuit 30 via thewater-refrigerant heat exchanger 22. However, heat medium subjected to aheat exchange with refrigerant is not limited to water, but any heatmedium is applicable, which enables heat transfer, such as antifreezesolution containing ethyleneglycol and so forth.

In addition, with the present embodiment, a configuration has beendescribed where the compressor 21 is driven by the electric motor 21 a.However, it is by no means limiting. A compressor 21 may be driven bythe power of an engine.

Moreover, the vehicle air conditioning apparatus is applicable not onlyto an electric car or a hybrid car, but applicable to other vehicles aslong as the vehicle air conditioning apparatus can compensate for aninsufficient quantity of heating for the heating or the heating anddehumidifying operation by electric power.

In addition, with the present embodiment, a configuration has beendescribed where the three-way valve 25 is used to switch between therefrigerant flow passages 20 c and 20 d in the refrigerant circuit 20.It is by no means limiting. Two solenoid valves are applicable insteadof the three-way valve, and therefore it is possible to switch betweenthe refrigerant flow passages 20 c and 20 d by opening and closing thesesolenoid valves.

Moreover, with the present embodiment, as the temperature of the waterhaving been heated in the water-refrigerant heat exchanger 22, theestimated water temperature TWhp is used, which is calculated based onthe temperature Tco of the refrigerant having released the heat in thewater-refrigerant heat exchanger 22 and the temperature efficiencyallowing for the flow rate GW flowing through the water circuit 30.However, another configuration is possible where the temperature of thewater having been heated in the water-refrigerant heat exchanger 22 isactually detected and the result of the detection is used.

FIG. 28 to FIG. 35 show Embodiment 9 of the present invention.

The vehicle air conditioning apparatus according to the presentinvention is applicable to an electric car that is run by electric powerand that is driven by the electric power of a battery to be used to runthe electric car. As shown in FIG. 28, this vehicle air conditioningapparatus includes an air conditioning unit 10 provided in the vehicleinterior, and a refrigerant circuit 20 and a water circuit 30 that areformed across the vehicle interior and the outdoor.

The air conditioning unit 10 includes an air flow passage 11 that allowsthe air to be supplied to the vehicle interior to pass through. Anoutdoor air inlet 11 a and an indoor air inlet 11 b are provided in thefirst end side of the air flow passage 11. The outdoor air inlet 11 a isconfigured to allow the outdoor air to flow into the air flow passage11, and the indoor air inlet 11 b is configured to allow the indoor airto flow into the air flow passage 11. Meanwhile, a foot outlet 11 c, avent outlet 11 d and a defroster outlet 11 e are provided in the secondend side of the air flow passage 11. The foot outlet 11 c is configuredto allow the air flowing through the air flow passage 11 to blow to thefeet of the passengers in the vehicle. The vent outlet 11 d isconfigured to allow the air flowing through the air flow passage 11 toblow to the upper bodies of the passengers in the vehicle. The defrosteroutlet 11 e is configured to allow the air flowing through the air flowpassage 11 to blow to the interior surface of the front window.

An indoor fan 12 such as a sirocco fan configured to allow the air toflow through the air flow passage 11 from end to end is provided in thefirst end side of the air flow passage 11. This indoor fan 12 is drivenby the electric motor 12 a.

Also, in the first end side of the air flow passage 11, an inletswitching damper 13 configured to open one of the outdoor air inlet 11 aand the indoor air inlet 11 b and to close the other. This inletswitching damper 13 is driven by the electric motor 13 a. When the inletswitching damper 13 closes the indoor air inlet 11 b and opens theoutdoor air inlet 11 a, the mode is switched to an outdoor air supplymode in which the airflows from the outdoor air inlet 11 a into the airflow passage 11. Meanwhile, when the inlet switching damper 13 closesthe outdoor air inlet 11 a and opens the indoor air inlet 11 b, the modeis switched to an indoor air circulation mode in which the air flowsfrom the indoor air inlet 11 b into the air flow passage 11. Moreover,when the inlet switching damper 13 is placed between the outdoor airinlet 11 a and the indoor air inlet 11 b and the outdoor air inlet 11 aand the indoor air inlet 11 b open, the mode is switched to a two-waymode in which the air flows from both the outdoor air inlet 11 a and theindoor air inlet 11 b into the air flow passage 11 according to theopening ratio of the outdoor air inlet 11 a and the indoor air inlet 11b.

Outlet switching dampers 13 b, 13 c and 13 d configured to open andclose the foot outlet 11 c, the vent outlet 11 d and the defrosteroutlet 11 e are provided in the foot outlet 11 c, the vent outlet 11 dand the defroster outlet 11 e, respectively, in the second side of theair flow passage 11. These outlet switching dampers 13 b, 13 c and 13 dare configured to move together by a linkage and are opened and closedby the electric motor 13 e. Here, when the outlet switching dampers 13b, 13 c and 13 d open the foot outlet 1 c, close the bent outlet 11 dand slightly open the defroster outlet 11 e, most of the air flowingthrough the air flow passage 11 blows out of the foot outlet 11 c andthe remaining air blows out of the defroster outlet 11 e. This mode isreferred to as “foot mode.” Meanwhile, when the outlet switching dampers13 b, 13 c and 13 d close the foot outlet 11 c and the defroster outlet11 e, and open the vent outlet 11 d, all the air flowing through the airflow passage 11 blows out of the vent outlet 11 d. This mode is referredto as “vent mode.” In addition, when the outlet switching dampers 13 b,13 c and 13 d open the foot outlet 11 c and the vent outlet 11 d, andclose the defroster outlet 11 e, the air flowing through the air flowpassage 11 blows out of the foot outlet 11 c and the vent outlet 11 d.This mode is referred to as “bi-level mode.” Moreover, when the outletswitching dampers 13 b, 13 c and 13 d close the foot outlet 11 c and thevent outlet 11 d, and open the defroster outlet 11 e, the air flowingthrough the air flow passage 11 blows out of the defroster outlet 11 e.This mode is referred to as “defroster mode.” Furthermore, when theoutlet switching dampers 13 b, 13 c and 13 d close the vent outlet 11 dand open the foot outlet 11 c and the defroster outlet 11 e, the airflowing through the air flow passage 11 blows out of the foot outlet 11c and the defroster outlet 11 e. This mode is referred to as“defroster-foot mode.” Here, in the bi-level mode, the air flow passage11, the foot outlet 11 c, the vent outlet 11 d, and a heat exchanger anda radiator which will be described later, are arranged and configuredsuch that the temperature of the air blowing out of the foot outlet 11 cis higher than the temperature of the air blowing out of the vent outlet11 d.

A heat exchanger 14 is provided in the air flow passage 11 in thedownstream of the air flow from the indoor fan 12. The heat exchanger 14is configured to cool and dehumidify the air flowing through the airflow passage 11. In addition, a radiator 15 is provided in the air flowpassage 11 in the downstream of the air flow from the heat exchanger 14.The radiator 15 is configured to heat the air flowing through the airflow passage 11. The heat exchanger 14 is a heat exchanger that isconstituted by fins and tubes and that is configured to perform heatexchange between the refrigerant flowing through the refrigerant circuit20 and the air flowing through the air flow passage 11. Meanwhile, theradiator 15 is a heat exchanger that is constituted by fins and tubesand that is configured to perform heat exchange between the waterflowing through the water circuit 30 and the air flowing through the airflow circuit 11.

An air mix damper 16 is provided between the heat exchanger 14 and theradiator 15 in the air flow passage 11 and is configured to control thepercentage of the air to be heated, which is flowing through the airflow passage 11. The air mix damper 16 is driven by the electric motor16 a. When the air mix damper 16 is disposed in the air flow passage 11in the upstream of the radiator 15, the percentage of the air subjectedto a heat exchange in the radiator 15 is reduced. Meanwhile, when theair mix damper 16 is moved to a position other than the radiator 15 inthe air flow passage 11, the percentage of the air subjected to a heatexchange is increased. In the air flow passage 11, when the air mixdamper 16 closes the upstream side of the radiator 15 and opens theportion other than the radiator 15, the opening degree is 0%, and, onthe other hand, when the air mix damper 16 opens the upstream side ofthe radiator 15 and closes the portion other than the radiator 15, theopening degree is 100%.

The refrigerant circuit 20 includes: the heat exchanger 14; a compressor21 configured to compress refrigerant; a water-refrigerant heatexchanger 22 configured to perform a heat exchange between therefrigerant and the water flowing through the water circuit 30; anoutdoor heat exchanger 23 configured to perform a heat exchange betweenthe refrigerant and the outdoor air; an indoor heat exchanger 24configured to perform a heat exchange between the refrigerant flowinginto heat exchanger 14 and the refrigerant flowing out of the heatexchanger 14; a three-way valve 25 configured to switch the passage ofthe refrigerant; first to fourth solenoid valves 26 a to 26 d; first andsecond check valves 27 a and 27 b; and first and second expansion valves28 a and 28 b configured to decompress the refrigerant. These componentsare connected to each other by a copper pipe or an aluminum pipe. Thecompressor 21 and the outdoor heat exchanger 23 are disposed outside thevehicle interior. The compressor 21 is driven by the electric motor 21a. The outdoor heat exchanger 23 is provided with an outdoor fan 29configured to perform heat exchange between the outdoor air and therefrigerant when the vehicle stops. The outdoor fan 29 is driven by theelectric motor 29 a.

To be more specific, one side of the water-refrigerant heat exchanger 22into which the refrigerant flows is connected to one side of thecompressor 21 from which the refrigerant is discharged to form therefrigerant flow passage 20 a. In addition, the input side of theoutdoor heat exchanger 23 into which the refrigerant flows is connectedto the output side of the water-refrigerant heat exchanger 22 from whichthe refrigerant is discharged, thereby to form the refrigerant flowpassage 20 b. The refrigerant flow passage 20 b is provided with thethree-way valve 25. The one side of the three-way valve 25 from whichthe refrigerant is discharged and another side from which therefrigerant is discharged are parallel to one another and are connectedto the input side of the outdoor heat exchanger 23 into which therefrigerant flows and thereby to form the refrigerant flow passages 20 cand 20 d. The refrigerant flow passage 20 d is provided with the firstexpansion valve 28 a and the first check valve 27 a in the order fromthe upstream of the flow of the refrigerant. The input side of thecompressor 21 into which the refrigerant is sucked and the part of therefrigerant flow passage 20 d between the three-way valve 25 and thefirst expansion valve 28 a are connected in parallel to the output sideof the outdoor heat exchanger 23 from which the refrigerant isdischarged, thereby to form the refrigerant flow passage 20 e and 20 f.The refrigerant flow passage 20 e is provided with the first solenoidvalve 26 a. The refrigerant flow passage 20 f is provided with thesecond solenoid valve 26 b and the second check valve 27 b in the orderfrom the upstream of the flow of the refrigerant. The input side of theinterior heat exchanger 24 into which high-pressure refrigerant flows isconnected to the part of the refrigerant flow passage 20 d between thethree-way valve 25 and the first expansion valve 28 a, thereby to formthe refrigerant flow passage 20 g. The refrigerant passage 20 g isprovided with the third solenoid valve 26 c. The input side of the heatexchanger 14 into which the refrigerant flow is connected to the outputside of the indoor heat exchanger 24 from which the high-pressurerefrigerant is discharged, thereby to provide the refrigerant flowpassage 20 h. The refrigerant flow passage 20 h is provided with thesecond expansion valve 28 b. The input side of the indoor heat exchanger24 into which low-pressure refrigerant flows is connected to the outputside of the heat exchanger 14 from which the refrigerant is discharged,thereby to form the refrigerant flow passage 20 i. The part of therefrigerant flow passage 20 e between the first solenoid valve 26 a andthe input side of the compressor 21 into which the refrigerant is suckedis connected to the output side of the indoor heat exchanger 24 fromwhich the low-pressure refrigerant is discharged, thereby to provide therefrigerant flow passage 20 j. The input side of the outdoor heatexchanger 23 into which the refrigerant flows is connected to therefrigerant flow passage 20 a, thereby to provide the refrigerant flowpassage 20 k. The refrigerant flow passage 20 k is provided with thefourth solenoid valve 26 d.

The water circuit 30 includes the radiator 15, the water-refrigerantheat exchanger 22, a pump 31 configured to pump the water as heat mediumand a water heater 32 such as an electric heater configured to heatwater by electric power. These components are connected by a copper pipeor an aluminum pipe. To be more specific, the input side of thewater-refrigerant heat exchanger 22 into which water flows is connectedto output side of the pump 31 from which the water is discharged,thereby to form a water flow passage 30 a. The input side of the waterheater 32 into which the water flows is connected to the output side ofthe water-refrigerant heat exchanger 22 from which the water isdischarged, thereby to from a water flow passage 30 b. The input side ofthe radiator 15 into which the water flows is connected to the outputside of the water heater 32 from which the water is discharged, therebyto form a water flow passage 30 c. The input side of the pump 31 intowhich the water is sucked is connected to the output side of theradiator 15 from which the water flows, thereby to from a water flowpassage 30 d. The pump 31 is driven by the electric motor 31 a.

The vehicle air conditioning apparatus also includes a controller 40that controls the temperature and the humidity of the vehicle interiorto be the preset temperature and humidity.

The controller 40 includes a CPU, a ROM and a RAM. In the controller,upon receiving an input signal from a device connected to the inputside, the CPU reads the program stored in the ROM according to the inputsignal, stores the state detected by the input signal on the RAM andtransmits an output signal to a device connected to the output side.

As shown in FIG. 29, an outdoor air temperature sensor 41 configured todetect temperature Tam outside the vehicle interior; an indoor airtemperature sensor 42 configured to detect temperature Tr in the vehicleinterior; an intake temperature sensor 43 configured to detecttemperature Ti of the air flowing into the air flow passage 11; a cooledair temperature sensor 44 configured to detect temperature Te of the airhaving been cooled in the heat exchanger 14; a heated air temperaturesensor 45 configured to detect temperature Tc of the air having beenheated in the radiator 15; an indoor air humidity sensor 46 configuredto detect humidity Th in the vehicle interior; a refrigerant temperaturesensor 47 configured to detect temperature Thex of the refrigerant afterthe heat exchange in the outdoor heat exchanger 23; an insolation sensor48 such as a photo sensor configured to detect amount of insolation Ts;a velocity sensor 49 configured to detect velocity V of the vehicle; anoperation part 50 configured to set modes regarding to target settingtemperature Tset and the switching of the operation; a pressure sensor51 configured to detect pressure Pd in the high-pressure side of therefrigerant circuit 20; and an outdoor air humidity sensor 53 configuredto detect humidity Rham outside the vehicle interior are connected tothe input side of the controller 40.

As shown in FIG. 29, an electric motor 12 a for driving the indoor fan12; an electric motor 13 a for driving the inlet switching damper 13; anelectric motor 13 e for driving the outlet switching dampers 13 b, 13 cand 13 d; an electric motor 16 e for driving the air mix damper 16; anelectric motor 21 e for driving the compressor 21; the three-way valve25; the first to fourth solenoid valves 26 a, 26 b, 26 c and 26 d; anelectric motor 29 a for driving the outdoor fan 29; an electric motor 31a for driving the pump 31; the water heater 32; and a navigation device54 configured to measure the present location of the vehicle and toguide the route to the destination are connected to the output side ofthe controller 40. The navigation device 54 is configured to be able toacquire traffic information, for example, whether or not traffic jamoccurs in the route to the destination.

The vehicle air conditioning apparatus having the above-describedconfiguration performs cooling operation, cooling and dehumidifyingoperation, heating operation, first heating and dehumidifying operation,second heating and dehumidifying operation and defrost operation. Now,each operation will be explained.

First, the cooling operation will be explained. In the refrigerantcircuit 20, the flow passage of three-way valve is set to therefrigerant flow passage 20 c side; the second and third solenoid valves26 b and 26 c open and the first and fourth solenoid valves 26 a and 26d are closed; and the compressor 21 is operated. Meanwhile, theoperation of the pump 31 is stopped in the water circuit 30.

By this means, as shown in FIG. 30, the refrigerant discharged from thecompressor 21 flows through in this order: the refrigerant flow passage20 a; the water-refrigerant heat exchanger 22; water-refrigerant flowpassages 20 b and 20 c; the outdoor heat exchanger 23, the refrigerantflow passages 20 f, 20 d and 20 g, the high-pressure side of theinternal heat exchanger 24; the refrigerant flow passage 20 h; the heatexchanger 14; the refrigerant flow passage 20 i; the low-pressure sideof the internal heat exchanger 24; and the refrigerant flow passages 20j and 20 e, and is sucked into the compressor 21. The refrigerantflowing through the refrigerant circuit 20 releases the heat in theoutdoor heat exchanger 23 and absorbs the heat in the heat exchanger 14.Since the pump 31 is stopped in the cooling operation, heat is notreleased from refrigerant in the water-refrigerant heat exchanger 22.

In this case, in the air conditioning unit 10 during the coolingoperation, the indoor fan 12 is operated to flow the air through the airflow passage 11, and the air is subjected to a heat exchange with therefrigerant in the heat exchanger 14 and cooled. The temperature of thecooled air is the target air-blowing temperature TAO of the air to blowout of the outlets 11 c, 11 d and 11 e in order to set the temperatureof the vehicle interior to target setting temperature Tset. Then, theair at temperature Tset blows to the vehicle interior.

Next, the cooling and dehumidifying operation will be explained. In therefrigerant circuit 20, like the cooling operation, the flow passage ofthe three-way valve 25 is set to the refrigerant flow passage 20 c side;the second and third solenoid valves 26 b and 26 c open and the firstand fourth solenoid valves 26 a and 26 d are closed; and the compressor21 is operated. In the water circuit 30, the pump 31 is operated.

By this means, as shown in FIG. 30, the refrigerant discharged from thecompressor 21 flows through in the same way as in the cooling operation.The refrigerant flowing through the refrigerant circuit 20 releases theheat in the water-refrigerant heat exchanger 22 and the outdoor heatexchanger 23, and absorbs the heat in the heat exchanger 14.

In addition, the water discharged from the pump 31 flows through in thisorder: the water-refrigerant heat exchanger 22, the water heater 32; andthe radiator 15 as indicated by the chain line of FIG. 30, and is suckedinto the pump 31. The water flowing through the water circuit 30 absorbsthe heat in the water-refrigerant heat exchanger 22 and releases theheat in the radiator 15.

In this case, in the air conditioning unit 10 during the cooling anddehumidifying operation, the indoor fan 12 is operated to flow the airthrough the air flow passage 11, and the air is subjected to a heatexchange with the refrigerant which absorbs the heat in the heatexchanger 14, and therefore is cooled and dehumidified. The air havingbeen dehumidified in the heat exchanger 14 is subject to heat exchangewith the water which releases the heat in the radiator 15, and thereforeheated. As a result, the air at the target air-blowing temperature TAOblows to the vehicle interior.

Next, the heating operation will be explained. In the refrigerantcircuit 20, the flow passage of the three-way valve 25 is set to therefrigerant flow passage 20 d side; the first solenoid valve 26 a opensand the second to fourth solenoid valves 26 b to 26 d are closed: andthe compressor 21 is operated. In the water circuit 30, the pump 31 isoperated.

By this means, as shown in FIG. 31, the refrigerant discharged from thecompressor 21 flows through this order: the refrigerant flow passage 20a; the water-refrigerant heat exchanger 22; the refrigerant flowpassages 20 b and 20 d; the outdoor heat exchanger 23; and therefrigerant flow passage 20 e, and is sucked into the compressor 21. Therefrigerant flowing through the refrigerant circuit 20 releases the heatin the water-refrigerant heat exchanger 22 and absorbs the heat in theoutdoor heat exchanger 23.

Meanwhile, as shown in FIG. 31, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22;the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22 and releases the heat in theradiator 15.

In this case, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11, and theflowing air is not subject to a heat exchange with the refrigerant inthe heat exchanger 14, but is subjected to a heat exchange with thewater in the radiator 15 and therefore is heated. As a result, the airat the target air-blowing temperature TAO blows to the vehicle interior.

Next, the first heating and dehumidifying operation will be explained.In the refrigerant circuit 20, the flow passage of the three-way valve25 is set to the refrigerant flow passage 20 d side; the first and thirdsolenoid valves 26 a and 26 c open and the second and fourth solenoidvalves 26 b and 26 d are closed; and the compressor 21 is operated.Meanwhile, the pump 31 is operated in the water circuit 30.

By this means, as shown in FIG. 32, the refrigerant discharged from thecompressor 21 flows through in this order: the refrigerant flow passage20 a; the water-refrigerant heat exchanger 22; and the refrigerant flowpassages 20 b and 20 d. Part of the refrigerant flowing through therefrigerant flow passage 20 d flows through in this order: the outdoorheat exchanger 23; and the refrigerant flow passage 20 e, and is suckedinto the compressor 21. In addition, remaining refrigerant flowingthrough the refrigerant flow passage 20 d flows through in this order:the refrigerant flow passage 20 g; the high-pressure side of theinterior heat exchanger 24; the refrigerant flow passage 20 h; the heatexchanger 14; the refrigerant flow passage 20 i; the low-pressure sideof the interior heat exchanger 24; and the refrigerant flow passages 20j and 20 e, and is sucked into the compressor 21. The refrigerantflowing through the refrigerant circuit 20 releases the heat in thewater-refrigerant heat exchanger 22 and absorbs the heat in the heatexchanger 14 and the outdoor heat exchanger 23.

Meanwhile, as shown in FIG. 32, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22;the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22 and releases the heat from theradiator 15.

In this case, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11, and theflowing air is subjected to a heat exchange with the refrigerant in theheat exchanger 14, and therefore is cooled and dehumidified. Part of theair having been dehumidified in the heat exchanger 14 is subjected to aheat exchange with the water in the radiator 15 and heated. As a result,the air at the target air-blowing temperature TAO blows into the vehicleinterior.

Next, the second heating and dehumidifying operation will be explained.In the refrigerant circuit 20, the flow passage of the three-way valve25 is set to the refrigerant flow passage side 20 d; the third solenoidvalve 26 c opens and the first, second and fourth solenoid valves 26 a,26 b and 26 d are closed; and the compressor 21 is operated. Meanwhile,the pump 31 is operated in the water circuit 30.

By this means, as shown in FIG. 33, the refrigerant discharged from thecompressor 21 flows through in this order: the refrigerant flow passage20 a; the water-refrigerant heat exchanger 22; the refrigerant flowpassages 20 b, 20 d and 20 g; the high-pressure side of the interiorheat exchanger 24; the refrigerant flow passage 20 h; the heat exchanger14; the refrigerant flow passage 20 i; the low-pressure side of theinterior heat exchanger 24; and the refrigerant flow passages 20 j and20 e, and is sucked into the compressor 21. The refrigerant flowingthrough the refrigerant circuit 20 releases the heat in thewater-refrigerant heat exchanger 22 and absorbs the heat in the heatexchanger 14.

Meanwhile, as shown in FIG. 33, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22;the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22 and releases the heat in theradiator 15.

In this case, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11, and theflowing air is subjected to a heat exchange with the refrigerant in theheat exchanger 14, and therefore is cooled and dehumidified in the sameway as in the first heating and dehumidifying operation. Part of the airdehumidified in the heat exchanger 14 is subjected to a heat exchangewith the water in the radiator 15, and therefore heated. As a result,the air at the target air-blowing temperature TAO blows to the vehicleinterior.

Next, the defrost operation will be explained. In the refrigerantcircuit 20, the flow passage of the three-way valve 25 is set to therefrigerant flow passage 20 d side; the first and fourth solenoid valves26 a and 26 d open and the second and third solenoid valves 26 d and 26c are closed; and the compressor 21 is operated. Meanwhile, the pump 31is operated in the water circuit 30.

By this means, as shown in FIG. 34, part of the refrigerant dischargedfrom the compressor 21 flows through in this order: the refrigerant flowpassage 20 a; the water-refrigerant heat exchanger 22; the refrigerantflow passages 20 b and 20, and flows into the outdoor heat exchanger 23.In addition, the remaining refrigerant discharged from the compressor 21flows through the refrigerant flow passages 20 a and 20 k and flows intothe outdoor heat exchanger 23. The refrigerant flowing out of theoutdoor heat exchanger 23 flows through the refrigerant flow passage 20e, and is sucked into the compressor 21. The refrigerant flowing throughthe refrigerant circuit 20 releases the heat in the water-refrigerantheat exchanger 22, and at this time, absorbs the heat in the outdoorheat exchanger 23.

Meanwhile, as shown in FIG. 34, the water discharged from the pump 31flows through in this order: the water-refrigerant heat exchanger 22,the water heater 32; and the radiator 15, and is sucked into the pump31. The water flowing through the water circuit 30 absorbs the heat inthe water-refrigerant heat exchanger 22, and releases the heat in theradiator 15.

In this case, in the air conditioning unit 10, the indoor fan 12 isoperated to flow the air through the air flow passage 11. The flowingair is not subjected to a heat exchange with the refrigerant in the heatexchanger 14, but is subjected to a heat exchange with the water whichreleases the heat in the radiator 15, and therefore is heated and thenblows to the vehicle interior.

While the automatic switch of the operation part 50 is turned on, thecontroller 40 performs an operation switching control process to switchamong the cooling operation, the cooling and dehumidifying operation,the heating operation, the first heating and dehumidifying operation,the second heating and dehumidifying operation, and the defrostoperation, based on indoor and outdoor environmental conditions, such astemperature.

In each operation switched by the operation switching control process,the controller 40 switches among the foot mode, the vent mode and thebi-level mode according to the target air-blowing temperature TAO. To bemore specific, when the target air-blowing temperature TAO is high, forexample, 40 degrees centigrade, the controller 40 sets the foot mode.Meanwhile, when the target air-blowing temperature TAO is low, forexample, lower than 25 degrees centigrade, the controller sets the ventmode. Moreover, when the target air-blowing temperature TAO is thetemperature between the temperature for the foot mode and thetemperature for the vent mode, the controller 40 sets the bi-level mode.

The controller 40 switches the mode of the outlets 11 c, 11 d and 11 eby using the outlet switching dampers 13 b, 13 c and 13 d, and controlsthe opening degree of the air mix damper 16 in order to set thetemperature of the air blowing out of the outlets 11 c, 11 d, and 11 eto the target air-blowing temperature TAO.

In addition, when the outdoor air temperature is low, for example, inwinter, the controller 40 determines whether or not a frost is formed onthe outdoor heat exchanger 23, and performs a defrost operation controlprocess to control the time of the start of the defrost operation, basedon the driving state of the vehicle and the power of the battery B todrive the vehicle. Now, the operation of the controller 40 in thisprocess will be explained with reference to the flowchart shown in FIG.35.

(Step 141)

In step S141, the CPU determines whether or not a frost is formed on theoutdoor heat exchanger 23. When determining that a frost is formed onthe outdoor heat exchanger 23, the CPU moves the step to step S142. Onthe other hand, when determining that a frost is not formed on theoutdoor heat exchanger 23, the CPU ends the defrost operation controlprocess. Here, a method of determining whether or not a frost is formedon the outdoor heat exchanger 23 will be explained. First, the CPUcalculates outdoor air dew point temperature Tdew, which is the dewpoint temperature of the outdoor air, based on the outdoor airtemperature Tam detected by the outdoor air temperature sensor 41 andthe outdoor humidity Rham detected by the outdoor humidity sensor 53.Next, the CPU determines whether or not the temperature Thex of therefrigerant flowing out of the outdoor heat exchanger 23, which has beendetected by the refrigerant temperature sensor 47, is lower than theoutdoor air dew point temperature Tdew. When the temperature Thex of therefrigerant is lower than the outdoor air dew point temperature Tdew,the CPU determines that a frost is formed on the outdoor heat exchanger23. This determination of whether or not a frost is formed on theoutdoor heat exchanger 23 is performed regardless of whether or not thevehicle is running.

(Step S142)

When determining that a frost is formed on the outdoor heat exchanger 23in the step S141, the CPU calculates an estimated amount of frost. Here,the estimated amount of frost is calculated by detecting, for example,the outdoor air temperature Tam, the temperature Thex and the pressureof the refrigerant after the heat exchange in the outdoor heat exchanger23, the velocity V of the vehicle, and the durations of the temperatureTam and the temperature Thex.

(Step S143)

In step S143, the CPU determines whether or not the power of the batteryB is a predetermined level or lower. When determining that the power ofthe battery B is a predetermined level or lower, the CPU moves the stepto step S145. On the other hand, when determining that the power of thebattery B is not a predetermined level or lower, the CPU moves the stepto step S144.

(Step S144)

When determining that the power of the battery B is not a predeterminedlevel or lower in the step S143, the CPU determines whether or not thevehicle is not running because the key is off in the step 144. Whendetermining that the key is off, the CPU moves the step to step S145. Onthe other hand, determining that the key is not off, that is, thevehicle is running, the CPU moves the step to step S147.

(Step S145)

When determining that the power of the battery B is a predeterminedlevel or lower in the step 143, or when determining that the vehicle isnot running because the key is off, the CPU determines whether or notthe battery is being charged in step the S145. When determining that thebattery B is being charged, the CPU moves the step to step S146. On theother hand, when determining that the battery B is not being charged,the CPU ends the defrost operation control process.

(Step S146)

When determining that the battery B is being charged in the step S145,the CPU determines whether or not the outdoor air temperature Tam is apredetermined temperature (e.g. 0 degree centigrade) or lower. Whendetermining that the temperature Tam is a predetermined temperature orlower, the CPU moves the step to step S151. On the other hand, whendetermining that the outdoor air temperature Tam is not a predeterminedtemperature or lower, the CPU moves the step to step S150.

(Step S147)

When determining that the key is on, and therefore the vehicle can runin the step S144, the CPU determines whether the estimated amount of thefrost on the outdoor heat exchanger 23 is a first predetermined level orhigher in step S147. When determining that the estimated amount of thefrost is the first predetermined amount or higher, the CPU moves thestep to the step S151. On the other hand, determining that the estimatedamount of the frost is not the first predetermined level or higher, theCPU moves the step to step S148.

(Step S148)

When determining that the estimated amount of the frost is not the firstpredetermined level or higher in the step S147, the CPU determineswhether or not the average velocity of the vehicle for a predeterminedperiod of time is a predetermined velocity (e.g. 30 km per hour) orlower in the step S148. When determining that the average velocity ofthe vehicle is a predetermined velocity or lower, the CPU moves the stepto the step S151. On the other hand, when determining that the averagevelocity of the vehicle is not a predetermined velocity or lower, theCPU moves the step to step S149. Here, the CPU determines whether or nota traffic jam has occurred on the road based on the average velocity ofthe vehicle for a predetermined period of time. Whether or not a trafficjam has occurred in the road can be determined by acquiring trafficinformation by using the navigation device 54.

(Step S149)

When determining that the average velocity of the vehicle for apredetermined period of time is not a predetermined velocity or lower inthe step S148, the CPU determines whether or not a traffic jam hasoccurred in the route to the destination based on the trafficinformation acquired by the navigation device 54. When determining thata traffic jam has occurred in the route to the destination, the CPU endsthe defrost operation control process. On the other hand, whendetermining that a traffic jam has not occurred in the route to thedestination, the CPU moves the step to the step S151.

(Step S150)

When determining that the outdoor air temperature Tam is not apredetermined temperature or lower in the step S146, the CPU determineswhether or not the estimated amount of the frost on the outdoor heatexchanger 23 is a second predetermined level or higher in the step S150.When determining that the estimated amount of the frost is the secondpredetermined level or higher, the CPU moves the step to the step S151.On the other hand, when determining that the estimated amount of thefrost is not the second predetermined level or higher, the CPU moves thestep to the step S154.

(Step S151)

The CPU performs the defrost operation in the step S151 on the followingconditions: it is determined in the step S146 that the outdoor airtemperature Tam is a predetermined temperature or lower; it isdetermined in the step S147 that the estimated amount of the frost isthe first predetermined level or higher; it is determined in the stepS148 that the average velocity of the vehicle is a predeterminedvelocity or lower; it is determined in the step S149 that a traffic jamhas not occurred in the route to the destination; or it is determined inthe step S150 that the estimated amount of the frost is the secondpredetermined level or higher.

(Step S152)

In step S152, the CPU determines whether or not a predetermined periodof time has elapsed after the defrost operation starts in the step S151.When determining that a predetermined period of time has elapsed afterthe defrost operation starts, the CPU moves the step to step S153. Onthe other hand, when determining that a predetermined period of time hasnot elapsed after the defrost operation starts, the CPU ends the defrostoperation control process. Here, a predetermined period of time havingelapsed after the defrost operation starts is set based on the estimatedamount of frost, the velocity V of the vehicle, the outdoor humidityRham, the air quantity of the outdoor fan 29 and so forth.

(Step S153)

When determining that a predetermined period of time has elapsed afterthe defrost operation starts in the step S152, the CPU stops the defrostoperation in the step S153 and ends the defrost operation controlprocess.

(Step S154)

When determining that the estimated amount of frost is not the secondpredetermined level or higher in the step S150, the CPU operates theoutdoor fan 29 in the step S154.

(Step S155)

In step S155, the CPU determines whether or not a predetermined periodof time has elapsed after the operation of the outdoor fan 29 is startedin the step S154. When determining that a predetermined period of timehas elapsed after the operation of the outdoor fan 29 is started, theCPU moves the step to step S156. On the other hand, when determiningthat a predetermined period of time has not elapsed after the operationof the outdoor fan 29 is started, the CPU ends the defrost operationcontrol process. Here, a predetermined time having elapsed after theoperation of the outdoor fan 29 is started is set based on the estimatedamount of frost, the velocity V of the vehicle, the outdoor humidityRham, the air quantity of the outdoor fan 29 and so forth.

(Step S156)

When determining that a predetermined period of time has elapsed afterthe operation of the outdoor fan 29 is started in the step S155, the CPUstops the operation of the outdoor fan 29 in the step S156 and ends thedefrost operation control process.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, in a case in which a frost isformed on the outdoor heat exchanger 23, the defrost operation is notperformed when the power of the battery B is a predetermined level orlower, but the defrost operation is started when the battery B is beingcharged. By this means, when the power of the battery B becomesinsufficient while the vehicle is running, it is possible to efficientlyuse the power of the battery B as the power to drive the vehicle.Therefore, it is possible to extend the mileage of the vehicle.

In addition, in a case in which a frost is formed on the outdoor heatexchanger 23, the defrost operation is not performed when the power ofthe battery B is a predetermined level or lower, but the outdoor fan 29is operated when the battery is being charged and the outdoor airtemperature Tam is 0 degree centigrade or higher. By this means it ispossible to help the frost to melt and also possible to blow off thewater resulting from the melting of the frost by using the outdoor fan29. Therefore, the defrost operation with high power consumption is notrequired.

In addition, the outdoor fan 29 is stopped after a predetermined periodof time has elapsed after the operation of the outdoor fan 29 isstarted. By this means, it is possible to prevent the outdoor fan 29from being operated more than necessary, and therefore to prevent anincrease in power consumption.

Moreover, the amount of the frost formed on the outdoor heat exchanger23 is calculated, and then the defrost operation is performed at thestart time that is determined based on the calculated amount of thefrost. By this means, it is possible to promptly perform the defrostoperation when the amount of the frost is large, and therefore toreliably prevent a problem: for example, that the amount of the frost onthe outdoor heat exchanger 23 is too large to perform the defrostoperation.

In addition, when the velocity of the vehicle is a predetermined levelor lower, the defrost operation is performed. By this means, it ispossible to perform the defrost operation when the vehicle is running ata low velocity with low power consumption, and therefore to prevent themileage of the vehicle from significantly dropping due to the defrostoperation.

In addition, the defrost operation is performed at the start time thatis determined based on the information acquired by the navigation device54. By this means, when the vehicle is running in the vicinity of thedestination, or when a traffic jam has occurred on the route to thedestination, it is possible to perform the defrost operation when thevehicle is stopped or when the velocity of the vehicle is apredetermined level or lower. Therefore, it is possible to prevent thedefrost operation from being performed when the vehicle is running at ahigh velocity with high power consumption.

Moreover, the defrost operation is stopped after a predetermined periodof time has elapsed from the defrost operation is started. By thismeans, it is possible to prevent the defrost operation from beingperformed more than necessary, and therefore to prevent an increase inpower consumption.

Furthermore, the outdoor air dew point temperature Tdew, which is thedew point temperature of the outdoor air, is calculated, and, when thetemperature Thex of the refrigerant flowing out of the outdoor heatexchanger 23 is lower than the outdoor air dew point temperature Tdew,it is determined that a frost is formed on the outdoor heat exchanger23. By this means, the defrost operation is performed when the outdoorheat exchanger 23 is a subjected to the conditions in which a frost isformed, and therefore to reliably prevent a frost from being formed onthe outdoor heat exchanger 23.

FIG. 36 shows Embodiment 10 of the present invention. Here, the samecomponents are assigned the same reference numerals as in Embodiment 9.

The controller 40 of this vehicle air conditioning apparatus performs adefrost operation control process shown by the flowchart in FIG. 36. Thedefrost operation control process is different between Embodiment 9 andEmbodiment 10 in that Embodiment 9 has a preference to secure themileage of the vehicle, but Embodiment 10 has a preference to reliablyprevent a frost from being formed on the outdoor heat exchanger 23.

(Step S161)

In step S161, the CPU determines whether or not a frost is formed on theoutdoor heat exchanger 23. When determining that a frost is formed onthe outdoor heat exchanger 23, the CPU moves the step to step S162. Onthe other hand, when determining that a frost is not formed on theoutdoor heat exchanger 23, the CPU ends the defrost operation controlprocess.

(Step S162)

When determining that a frost is formed on the outdoor heat exchanger 23in the step S161, the CPU calculates an estimated amount of frost.

(Step S163)

In step S163, the CPU determines whether or not the estimated amount ofthe frost of the outdoor heat exchanger 23 is a first predeterminedlevel or higher. When determining that the estimated amount of the frostis the first predetermined level or higher, the CPU moves the step tostep S171. On the other hand, when determining that the estimated amountof the frost is not the first predetermined level or higher, the CPUmoves the step to step S164.

(Step S164)

When determining that the estimated amount of the frost is not the firstpredetermined level or higher in the step S163, the CPU determineswhether or not the power of the battery B is a predetermined level orlower in the step S164. When determining that the power of the battery Bis a predetermined level or lower, the CPU moves the step to step S166.On the other hand, when determining that the power of the battery B isnot a predetermined level or lower, the CPU moves the step to step S165.

(Step S165)

When determining that the power of the battery B is not a predeterminedlevel or lower in the step S164, the CPU determines whether or not thevehicle is not running because the key is off in the step S165. Whendetermining that the key is off, the CPU moves the step to step S166. Onthe other hand, when determining that the key is not off, that is, thevehicle is running, the CPU moves the step to step S168.

(Step S166)

When determining that the power of the battery B is a predeterminedlevel or lower in the step S164, or when determining that the vehicle isnot running because the key is off, the CPU determines whether or notthe battery B is being charged in the step S166. When determining thatthe battery B is being charged, the CPU moves the step to step S167. Onthe other hand, when determining that the battery B is not beingcharged, the CPU ends the defrost operation control process.

(Step S167)

When determining that the battery B is being charged in the step S166,the CPU determines whether or not outdoor air temperature Tam is apredetermined temperature (e.g. 0 degree centigrade) or lower in thestep S167. When determining that the temperature Tam is a predeterminedtemperature or lower, the CPU moves the step to step S171. On the otherhand, when determining that the outdoor air temperature Tam is not apredetermined temperature or lower, the CPU moves the step to step S170.

(Step S147)

When determining that the key is not off in the step S165, the CPUdetermines whether or not the average velocity of the vehicle for apredetermined period of time is a predetermined velocity or lower instep S168. When determining that the average velocity is a predeterminedvelocity or lower, the CPU moves the step to the step S171. On the otherhand, when the average velocity is not a predetermined velocity orlower, the CPU moves the step to step S169.

(Step S169)

When determining that the average velocity of the vehicle for apredetermined period of time is not a predetermined velocity or lower inthe step S169, the CPU determines whether or not a traffic jam hasoccurred in the route to the destination based on the trafficinformation acquired by the navigation device 54. When determining thata traffic jam has occurred in the route to the destination, the CPU endsthe defrost operation control process. On the other hand, whendetermining that a traffic jam has not occurred in the route to thedestination, the CPU moves the step to the step S171.

(Step S150)

When determining that the outdoor air temperature Tam is not apredetermined temperature or lower in the step S167, the CPU determineswhether or not the estimated amount of the frost on the outdoor heatexchanger 23 is a second predetermined level or higher in the step S170.When determining that the estimated amount of the frost is the secondpredetermined level or higher, the CPU moves the step to the step S171.On the other hand, when determining that the estimated amount of thefrost is not the second predetermined level or higher, the CPU moves thestep to the step S174.

(Step S171)

The CPU performs the defrost operation in the step S171 on the followingconditions: it is determined in the step S167 that the outdoor airtemperature Tam is a predetermined temperature or lower; it isdetermined in the step S163 that the estimated amount of the frost isthe first predetermined level or higher; it is determined in the stepS168 that the average velocity of the vehicle is a predeterminedvelocity or lower; it is determined in the step S169 that a traffic jamhas not occurred in the route to the destination; or it is determined inthe step S170 that the estimated amount of the frost is the secondpredetermined level or higher.

(Step S172)

In step S172, the CPU determines whether or not a predetermined periodof time has elapsed after the defrost operation starts in the step S151.When determining that a predetermined period of time has elapsed afterthe defrost operation starts, the CPU moves the step to step S173. Onthe other hand, when determining that a predetermined period of time hasnot elapsed after the defrost operation starts, the CPU ends the defrostoperation control process.

(Step S173)

When determining that a predetermined period of time has elapsed afterthe defrost operation starts in the step S172, the CPU stops the defrostoperation in the step S173 and ends the defrost operation controlprocess.

(Step S174)

When determining that the estimated amount of frost is not the secondpredetermined level or higher in the step S170, the CPU operates theoutdoor fan 29 in the step S174.

(Step S175)

In step S175, the CPU determines whether or not a predetermined periodof time has elapsed after the operation of the outdoor fan 29 is startedin the step S174. When determining that a predetermined period of timehas elapsed after the operation of the outdoor fan 29 is started, theCPU moves the step to step S176. On the other hand, when determiningthat a predetermined period of time has not elapsed after the operationof the outdoor fan 29 is started, the CPU ends the defrost operationcontrol process.

(Step S176)

When determining that a predetermined period of time has elapsed afterthe operation of the outdoor fan 29 is started in the step S174, the CPUstops the operation of the outdoor fan 29 in the step S176 and ends thedefrost operation control process.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, in the same way as in Embodiment 9,when the power of the battery B becomes insufficient while the vehicleis running, it is possible to efficiently use the power of battery asthe power to drive the vehicle. Therefore, it is possible to extend themileage of the vehicle.

FIG. 37 shows Embodiment 11 of the present invention. Here, the samecomponents are assigned the same reference numerals as in Embodiment 10.

This vehicle air conditioning apparatus is configured to be able to setthe start time of the defrost operation. The controller 40 performs adefrost operation control process shown by the flowchart in FIG. 37.

(Step S181)

In step S181, the CPU determines whether or not a frost is formed on theoutdoor heat exchanger 23. When determining that a frost is formed onthe outdoor heat exchanger 23, the CPU moves the step to step S182. Onthe other hand, when determining that a frost is not formed on theoutdoor heat exchanger 23, the CPU ends the defrost operation controlprocess.

(Step S182)

When determining that a frost is formed on the outdoor heat exchanger 23in the step S181, the CPU determines whether or not the vehicle is notrunning because the key is off. When determining that the key is off,the CPU moves the step to step S183. On the other hand, when determiningthat the key is not off, the CPU ends the defrost operation controlprocess.

(Step S183)

When determining that the key is off in the step S182, the CPUdetermines whether or not it is the set time to start the defrostoperation in the step S183. When determining that it is the set time tostart the defrost operation, the CPU moves the step to step S184. On theother hand, when determining that it is not the set time to start thedefrost operation, the CPU ends the defrost operation control process.

(Step S184)

When determining that it is the set time to start the defrost operationin the step S183, the CPU performs the defrost operation in the stepS184.

(Step S185)

In step S185, the CPU determines whether or not a predetermined periodof time has elapsed after the defrost operation is started in the stepS184. When determining that a predetermined period of time has elapsedafter the defrost operation is started, the CPU moves the step to stepS186. On the other hand, when determining that a predetermined period oftime has not elapsed after the defrost operation is started, the CPUends the defrost operation control process.

(Step S186)

When determining that a predetermined period of time has elapsed afterthe defrost operation is started in the step S185, the CPU stops thedefrost operation in the step S186 and ends the defrost operationcontrol process.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, the defrost operation is performedat the set time. By this means, it is possible to perform the defrostoperation just before the vehicle starts to run, so that there is noneed to perform the defrost operation several times while the vehicledoes not run. Therefore, it is possible to reduce the power consumptionfor the defrost operation.

FIG. 38 shows Embodiment 12 of the present invention. Here, the samecomponents are assigned the same reference numerals as in Embodiment 11.

This vehicle air conditioning apparatus is configured to store the timesto start to run the vehicle for a predetermined period of time of thepast, and to be able to calculate an estimated time to start to run thevehicle based on the stored times. The controller performs a defrostoperation control process shown by the flowchart in FIG. 38.

(Step S191)

In step S191, the CPU determines whether or not a frost is formed on theoutdoor heat exchanger 23. When determining that a frost is formed onthe outdoor heat exchanger 23, the CPU moves the step to step S192. Onthe other hand, when determining that a frost is not formed on theoutdoor heat exchanger 23, the CPU ends the defrost operation controlprocess.

(Step S192)

When determining that a frost is formed on the outdoor heat exchanger 23in the step S191, the CPU determines whether or not the vehicle is notrunning because the key is off. When determining that the key is off,the CPU moves the step to step S193. On the other hand, when determiningthat the key is not off, the CPU ends the defrost operation controlprocess.

(Step S193)

When determining that the key is off in the step S192, the CPUcalculates the estimated time to start to run the vehicle based on thetimes to start to run the vehicle in a predetermined period of time ofthe past in step S193. Here, the estimated time to start to run thevehicle is calculated based on, for example, the average of the actualtimes to start to run the vehicle for a predetermined period of time ofthe past.

(Step 194)

In step S194, the CPU calculates the start time of the defrost operationbased on the estimated time to start to run the vehicle calculated inthe step S193. Here, the start time of the defrost operation iscalculated by going back the period of time required for the defrostoperation from the time to start to run the vehicle.

(Step S195)

In step S195, the CPU determines whether or not it is the time to startthe defrost operation calculated in the step S194. When determining thatit is the time to start the defrost operation, the CPU moves the step tostep S196. On the other hand, when determining that it is not the timeto start the defrost operation, the CPU ends the defrost operationcontrol process.

(Step S196)

When determining that it is the time to start the defrost operation,which is set in the step 195, the CPU performs the defrost operation inthe step S196.

(Step S197)

In step S197, the CPU determines whether or not a predetermined periodof time has elapsed after the defrost operation is started in the stepS196. When determining that a predetermined period of time has elapsedafter the defrost operation is started, the CPU moves the step to stepS198. On the other hand, when determining that a predetermined period oftime has elapsed after the defrost operation is started, the CPU endsthe defrost operation control process.

(Step S198)

When determining that a predetermined period of time has elapsed afterthe defrost operation is started in the step S197, the CPU stops thedefrost operation in the step S198 and ends the defrost operationcontrol process.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, the defrost operation is stopped atthe estimated time to start to run the vehicle. By this means, it ispossible to perform the defrost operation just before the vehicle startsto run, so that there is no need to perform the defrost operationseveral times while the vehicle does not run. Therefore, it is possibleto reduce the power consumption for the defrost operation.

FIG. 39 is Embodiment 13 of the present invention. Here, the samecomponents are assigned the same reference numerals as in Embodiment 12.

This vehicle air conditioning apparatus is configured to determinewhether or not a frost is formed on the outdoor heat exchanger 23 andalso determine whether or not to start the defrost operation based onthe outdoor air temperature Tam. In addition, when determining that afrost is formed on the outdoor heat exchanger 23 but determining not tostart the defrost operation, the CPU stops the compressor 21 to removethe frost on the outdoor heat exchanger 23. In this case, the controller40 performs a defrost operation control process shown by the flowchartin FIG. 39.

(Step S201)

In step S201, the CPU determines whether or not the temperature Thex ofthe refrigerant flowing out of the outdoor heat exchanger 23 is lowerthan the calculated outdoor air dew point temperature Tdew. Whendetermining that the temperature Thex of the refrigerant flowing out ofthe outdoor heat exchanger 23 is lower than the calculated outdoor airdew point temperature Tdew, the CPU moves the step to step S202. On theother hand, when determining that the temperature Thex of therefrigerant flowing out of the outdoor heat exchanger 23 is not lowerthan the calculated outdoor air dew point temperature Tdew, the CPU endsthe defrost operation control process.

(Step S202)

When determining that the temperature Thex of the refrigerant flowingout of the outdoor heat exchanger 23 is lower than the calculatedoutdoor air dew point temperature Tdew in the step S201, the CPUdetermines whether or not the temperature Thex of the refrigerantflowing out of the outdoor heat exchanger 23 is a predeterminedtemperature (e.g. 0 degree centigrade) or lower in the step S202. Whendetermining that the temperature Thex of the refrigerant flowing out ofthe outdoor heat exchanger 23 is a predetermined temperature or lower,the CPU moves the step to step S203. On the other hand, when determiningthat the temperature Thex of the refrigerant flowing out of the outdoorheat exchanger 23 is not a predetermined temperature or lower, the CPUends the defrost operation control process.

(Step S203)

When determining that that the temperature Thex of the refrigerantflowing out of the outdoor heat exchanger 23 is a predeterminedtemperature or lower in the step 202, the CPU determines whether or notthe outdoor air temperature Tam, which is detected by the outdoor airtemperature sensor 41, is a predetermined temperature (e.g. 0 degreecentigrade) or lower in the step S203. When determining that the outdoorair temperature Tam is a predetermined temperature or lower, the CPUmoves the step to step S204. On the other hand, when determining thatthe outdoor air temperature Tam is not a predetermined temperature orlower, the CPU moves the step to step S207.

(Step S204)

When determining that the outdoor air temperature Tam is a predeterminedtemperature (e.g. 0 degree centigrade) or lower in the step S203, theCPU starts the defrost operation in step S204.

(Step S205)

In step S205, the CPU determines whether or not a predetermined periodof time has elapsed after the defrost operation is started. Whendetermining that a predetermined period of time has elapsed after thedefrost operation is started, the CPU moves the step to step S206. Onthe other hand, when determining that a predetermined period of time hasnot elapsed after the defrost operation is started, the CPU ends thedefrost operation control process.

(Step S206)

When determining that a predetermined period of time has elapsed afterthe defrost operation is started in the step S205, the CPU stops thedefrost operation in the step S206 and ends the defrost operationcontrol process.

(Step S207)

When determining that the outdoor air temperature Tam is not apredetermined temperature (e.g. 0 degree centigrade) or lower, the CPUstops the compressor 21 in step S207.

(Step S208)

In step S208, the CPU determines whether or not a predetermined periodof time has elapsed after the compressor 21 is stopped. When determiningthat a predetermined period of time has elapsed after the compressor 21is stopped, the CPU moves the step to step S209. On the other hand, whendetermining that a predetermined period of time has not elapsed afterthe compressor 21 is stopped, the CPU ends the defrost operation controlprocess. Here, a predetermined period of time after the compressor 21 isstopped may be changed according to the velocity of the vehicle.

(Step S209)

When determining that a predetermined period of time has elapsed afterthe compressor 21 is stopped in the step S208, the CPU resumes theoperation of the compressor 21 in step 209, and ends the defrostoperation control process.

As described above, with the vehicle air conditioning apparatusaccording to the present embodiment, the outdoor air dew pointtemperature Tdew is calculated. Then, when the temperature Thex of therefrigerant flowing out of the outdoor heat exchanger 23 is lower thanthe outdoor air dew point temperature Tdew and also lower than apredetermined temperature, it is determined that a frost is formed onthe outdoor heat exchanger 23. By this means, the defrost operation isperformed when the outdoor heat exchanger 23 is subjected to theconditions in which a frost is formed on the outdoor heat exchanger 23,and therefore to reliably prevent a frost from being formed on theoutdoor heat exchanger 23.

In addition, when determining that a frost is formed on the outdoor heatexchanger 23, the CPU determines whether or not to start the defrostoperation based on outdoor air temperature Tam, and, when determiningthat the defrost operation is not performed, the CPU stops thecompressor 21. By this means, it is possible to remove the frost on theoutdoor heat exchanger 23 by stopping the compressor 21 when the outdoorair temperature Tam is higher than a predetermined temperature.Therefore, it is possible to reduce the energy consumption. There is anadvantage over hot gas defrost in that the temperature drop of the airblowing to the vehicle interior is low during the defrost operation.

Here, with the embodiments, an exemplary configuration of the defrostoperation as shown in FIG. 34 has been described where part of therefrigerant discharged from the compressor 21 flows into the outdoorheat exchanger 23 to melt the frost on the outdoor heat exchanger 23.The defrost operation is not limited to his as long as it is possible toremove the frost on the outdoor heat exchanger 23. Another configurationis possible where all the refrigerant discharged from the compressor 21flows into the outdoor heat exchanger 23 to melt the frost. In addition,another configuration is possible where an electric heater 23 isprovided in the outdoor heat exchanger 23 to melt the frost. Moreover,further another configuration is possible where when a frost is formedon the outdoor heat exchanger 23, the operation is switched to thesecond heating and dehumidifying operation shown in FIG. 33 to stop therefrigerant from flowing into the outdoor heat exchanger 23, and thefrost is melted by using the outdoor fan 29 and so forth.

In addition, the defrost operation according to the embodiments is notonly when a frost is formed on the outdoor heat exchanger 23 during theheating operation, but also when a frost is formed on the outdoor heatexchanger 23 during the first and second heating and dehumidifyingoperations.

In addition, with Embodiment 9 and Embodiment 10, a configuration hasbeen described where the determination to perform the defrost operationis based on the determination of whether or not the power of the batteryis a predetermined level or lower. It is by no means limiting. Anotherconfiguration is possible where the determination to perform the defrostoperation is based on, for example, the mileage of the vehicle that iscalculated based on the power of the battery, or calculated by anothermethod.

In addition, with the embodiments, an exemplary configuration has beendescribed where information indicating that, for example, the vehicle isrunning in the vicinity of the destination, or a traffic jam hasoccurred in the running route, is acquired by the navigation device 54.It is by no means limiting as long as it is possible to determine thatthe velocity of the vehicle is a predetermined level or lower.

Moreover, with the embodiments, an exemplary configuration has beendescribed where the heat released from the refrigerant circuit 20 isabsorbed in the water flowing through the water circuit 30 through thewater-refrigerant heat exchanger 22. The heat medium subjected to theheat exchange with the refrigerant is not limited to the water.

In addition, with the present embodiment, a configuration has beendescribed where the three-way valve 25 is used to switch between therefrigerant flow passages 20 c and 20 d in the refrigerant circuit 20.It is by no means limiting. Two solenoid valves are applicable insteadof the three-way valve, and therefore it is possible to switch betweenthe refrigerant flow passages 20 c and 20 d by opening and closing thesesolenoid valves.

Moreover, with the present embodiment, a configuration has beendescribed where the water flowing through the water circuit 30, which issubjected to the heat exchange with the refrigerant releasing the heatin the water-refrigerant heat exchanger 22 of the refrigerant circuit20, is heated by the water heater 32. It is by no means limiting. Forexample, the vehicle air conditioning apparatus may not have the watercircuit 30 but have an indoor radiator. The indoor radiator releases theheat of the refrigerant flowing through the refrigerant circuit 20directly in the air flow passage 11, and the air flowing through the airflow passage 11 may be directly heated by an electric heater. By thismeans, it is possible to produce the same effect as in the presentembodiment. Moreover, further another configuration is possible wherethe vehicle air conditioning apparatus includes an indoor radiatorconfigured to release the heat of the refrigerant flowing through therefrigerant circuit 20 directly in the air flow passage 11; a heatmedium circuit that allows the heat medium having heated by the electricheater to flow through is provided separately from the refrigerantcircuit 20; the heat of the heat medium heated by the electric heater isreleased in the air flow passage 11. By this means, it is possible toproduce the same effect as in the present embodiment.

With Embodiment 9, the process including the step S141 and so forth todetermine whether or not a frost is formed on the outdoor heat exchanger23 corresponds to a frost formation determination part of the presentinvention. In addition, with Embodiment 9, the process including thestep S151 and so forth to perform the defrost operation correspond to adefrost part of the present invention. With Embodiment 9, the processincluding the step S143 and so forth to detect the power of the batteryB corresponds to a battery power detection part of the presentinvention. In addition, with Embodiment 9, the process including thestep S143, S145 and so forth to determine that the power of the batteryB is a predetermined level or lower and to end the defrost operationcontrol process when it is determined that the battery B is not beingcharged corresponds to a defrost operation limiting part of the presentinvention. Moreover, with Embodiment 9, the process including the stepS145 and so forth to determine whether or not the battery B is beingcharged corresponds to a charge determination part of the presentinvention. Moreover, with Embodiment 9, the process including the stepS143, S145, S151 and so forth to determine that the power of the batteryB is a predetermined level or lower and to perform the defrost operationwhen the battery B is being charged, corresponds to a cancellation partof the present invention. Moreover, with Embodiment 9, the processincluding the step S146 and so forth to operate the outdoor fan 29without performing the defrost operation when the outdoor airtemperature Tam is a predetermined temperature or higher corresponds toa fan control part of the present invention. Moreover, with Embodiment9, the process including the step S142 to calculate the amount of thefrost formed on the outdoor heat exchanger 23 corresponds to a frostcalculation part of the present invention. Furthermore, with Embodiment9, the navigation device 54 corresponds to a route setting part and atraffic information acquisition part of the present invention.

REFERENCE SIGNS LIST

10 air conditioning unit; 14 heat exchanger; 15 radiator; 20 refrigerantcircuit; 20 a to 20 j refrigerant flow passage; 21 compressor; 22water-refrigerant heat exchanger; 23 outdoor heat exchanger; 25three-way valve; 26 a to 26 d first to fourth solenoid valve; 27 a and27 b first and second check valve; 28 a and 28 b first and secondexpansion valve; 30 water circuit; 32 water heater; 40 controller; 41outdoor air temperature sensor; 42 indoor air temperature sensor; 43intake temperature sensor; 44 cooling air temperature sensor; 45 heatedair temperature sensor; 46 indoor air humidity sensor; 47 refrigeranttemperature sensor; 48 insolation sensor; 49 velocity sensor; 50operation part; 51 pressure sensor; 52 display part; 53 outdoor humiditysensor; 54 navigation device; and B battery

1. A vehicle air conditioning apparatus comprising: a compressorconfigured to compress and discharge refrigerant; an indoor heatexchanger provided in a vehicle interior; and an outdoor heat exchangerprovided outside the vehicle interior, wherein the vehicle interior isheated by releasing heat from the refrigerant discharged from thecompressor in the indoor heat exchanger, and absorbing the heat into therefrigerant in the outdoor heat exchanger, the vehicle air conditioningapparatus further comprising: a frost formation determination partconfigured to determine whether or not a frost is formed on the outdoorheat exchanger; a defrost part configured to perform a defrost operationto remove the frost formed on the outdoor heat exchanger when the frostformation determination part determines that the frost is formed on theoutdoor heat exchanger; a battery power detection part configured todetect a power of a battery that supplies power for driving a vehicleand for performing a heating operation; a defrost restriction partconfigured to restrict the defrost part from performing the defrostoperation when the power of the battery detected by the battery powerdetection part is a predetermined level or lower; a charge determinationpart configured to determine whether or not the battery is beingcharged; and a cancellation part configured to cancel the restriction onthe performing of the defrost operation by the defrost restriction partwhen the charge determination part determines that the battery is beingcharged.
 2. The vehicle air conditioning apparatus according to claim 1,further comprising: a fan configured to allow air to flow through, theair being subjected to a heat exchange with the refrigerant flowingthrough the outdoor heat exchanger; a temperature detection partconfigured to detect a temperature outside the vehicle interior; and afan control part configured to, while the defrost restriction partrestricts the defrost operation from being performed, operate the fanwithout cancelling the restriction on the performing of the defrostoperation by the defrost restriction part when the charge determinationpart determines that the battery is being charged and the temperaturedetected by the temperature detection part is a predetermined level orhigher.
 3. The vehicle air conditioning apparatus according to claim 2,wherein the fan control part stops the fan after a predetermined periodof time has elapsed after operation of the fan is started.
 4. Thevehicle air conditioning apparatus according to claim 1, furthercomprising a frost formation calculation part configured to calculate anamount of a frost formed on the outdoor heat exchanger, wherein thedefrost part performs the defrost operation at a start time determinedbased on the amount of the frost calculated by the frost formationcalculation part.
 5. The vehicle air conditioning apparatus according toclaim 1, further comprising a velocity detection part configured todetect a velocity of a vehicle, wherein the defrost part performs thedefrost operation when the velocity detected by the velocity detectionpart is a predetermined value or lower.
 6. The vehicle air conditioningapparatus according to claim 1, further comprising: a route setting partconfigured to measure a current location of the vehicle and set arunning route to a destination; and a traffic information acquisitionpart configured to be able to acquire traffic information on the runningroute that is set by the running route setting part, wherein the defrostpart performs the defrost operation at the start time determined, basedon one of the running route set by the route setting part and thetraffic information acquired by the traffic information acquisitionpart.
 7. The vehicle air conditioning apparatus according to claim 1,wherein the defrost part performs the defrost operation at a set time.8. The vehicle air conditioning apparatus according to claim 1, furthercomprising a storage part configured to store a time to start to run thevehicle for a predetermined period of time, wherein the defrost partperforms the defrost operation such that defrost on the outdoor heatexchanger is terminated at an estimated time to start to run the vehiclethat is set based on the time to start to run the vehicle stored in thestorage part.
 9. The vehicle air conditioning apparatus according toclaim 1, wherein the defrost part stops the defrost operation after apredetermined period of time has elapsed after the defrost operation isstarted.
 10. The vehicle air conditioning apparatus according to claim1, further comprising: an outdoor air dew point temperature calculationpart configured to calculate a dew point temperature of outdoor air; andan evaporating temperature detection part configured to detect anevaporating temperature of the refrigerant in the outdoor heatexchanger, wherein the frost formation determination part determinesthat a frost is formed when the temperature detected by the evaporatingtemperature detection part is lower than the dew point temperaturecalculated by the outdoor air dew point temperature calculation part.11. The vehicle air conditioning apparatus according to claim 1, furthercomprising: an outdoor air dew point temperature calculation partconfigured to calculate a dew point temperature of outdoor air; and anevaporating temperature detection part configured to detect anevaporating temperature of the refrigerant in the outdoor heatexchanger, wherein the frost formation determination part determinesthat a frost is formed when the evaporating temperature detected by theevaporating temperature detection part is lower than the dew pointtemperature calculated by the outdoor air dew point temperaturecalculation part and when the temperature detected by the evaporatingtemperature detection part is a predetermined level or lower.
 12. Thevehicle air conditioning apparatus according to claim 11, furthercomprising: a temperature detection part configured to detect atemperature outside the vehicle interior; and a heating operation stoppart configured to stop the compressor without performing the defrostoperation by the defrost part, when the frost formation determinationpart determines that the frost is formed and when the temperaturedetected by the temperature detection part is higher than apredetermined level during the heating operation.
 13. The vehicle airconditioning apparatus according to claim 12, wherein the heatingoperation stop part resumes operation of the compressor after apredetermined period of time has elapsed after the compressor isstopped.